Carbon dioxide sequestration methods using group 2 silicates and chlor-alkali processes

ABSTRACT

The present invention relates to an energy efficient carbon dioxide sequestration processes whereby Group 2 silicate minerals and CO 2  are converted into limestone and sand using a two-salt thermolytic process that allows for the cycling of heat and chemicals from one step to another.

The present application is a national phase application under 35 U.S.C. §371 which claims priority to PCT Application No. PCT/US2012/028535 filed Mar. 9, 2012, which claims priority to U.S. Provisional Patent Application Ser. No. 61/451,101 filed Mar. 9, 2011, both of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention generally relates to the field of removing carbon dioxide from a source, such as the waste stream (e.g. flue gas) of a power plant, whereby Group 2 silicate minerals are converted into Group 2 chloride salts and SiO₂, Group 2 chloride salts are converted into Group 2 hydroxide and/or Group 2 hydroxychloride salts. These in turn may be reacted with carbon dioxide to form Group 2 carbonate salts, optionally in the presence of catalysts. These steps may be combined to form a cycle in which carbon dioxide is sequestered in the form of carbonate salts and byproducts from one or more steps, such as heat and chemicals, are re-used or recycled in one or more other steps.

II. Description of Related Art

Considerable domestic and international concern has been increasingly focused on the emission of CO₂ into the air. In particular, attention has been focused on the effect of this gas on the retention of solar heat in the atmosphere, producing the “greenhouse effect.” Despite some debate regarding the magnitude of the effect, all would agree there is a benefit to removing CO₂ (and other chemicals) from point-emission sources, especially if the cost for doing so were sufficiently small.

Greenhouse gases are predominately made up of carbon dioxide and are produced by municipal power plants and large-scale industry in site-power-plants, though they are also produced in any normal carbon combustion (such as automobiles, rain-forest clearing, simple burning, etc.). Though their most concentrated point-emissions occur at power-plants across the planet, making reduction or removal from those fixed sites an attractive point to effect a removal-technology. Because energy production is a primary cause of greenhouse gas emissions, methods such as reducing carbon intensity, improving efficiency, and sequestering carbon from power-plant flue-gas by various means has been researched and studied intensively over the last thirty years.

Attempts at sequestration of carbon (in the initial form of gaseous CO₂) have produced many varied techniques, which can be generally classified as geologic, terrestrial, or ocean systems. An overview of such techniques is provided in the Proceedings of First National Conference on Carbon Sequestration, (2001). To date, many if not all of these techniques are too energy intensive and therefore not economically feasible, in many cases consuming more energy than the energy obtained by generating the carbon dioxide. Alternative processes that overcome one or more of these disadvantages would be advantageous.

The referenced shortcomings are not intended to be exhaustive, but rather are among many that tend to impair the effectiveness of previously known techniques for removing carbon dioxide from waste streams; however, those mentioned here are sufficient to demonstrate that the methodologies appearing in the art have not been altogether satisfactory and that a significant need exists for the techniques described and claimed in this disclosure.

SUMMARY OF THE INVENTION

Disclosed herein are methods and apparatuses for carbon dioxide sequestration, including removing carbon dioxide from waste streams. In one aspect there are provided methods of sequestering carbon dioxide produced by a source, comprising:

(a) admixing a magnesium chloride salt and water in a first admixture under conditions suitable to form (i) magnesium hydroxide, magnesium oxide and/or MgCl(OH) and (ii) hydrogen chloride; (b) admixing (i) magnesium hydroxide, magnesium oxide and/or MgCl(OH), (ii) CaCl₂ and (iii) carbon dioxide produced by the source in a second admixture under conditions suitable to foam (iv) calcium carbonate, (v) a magnesium chloride salt, and (vi) water;

(c) separating the calcium carbonate from the second admixture; and

(d) admixing a Group 2 silicate mineral with hydrogen chloride under conditions suitable to form a Group 2 chloride salt, water, and silicon dioxide, where some the hydrogen chloride in this step is obtained from step (a) and wherein some of the hydrogen chloride is obtained from a chlor-alkali electrolytic cell, whereby the carbon dioxide is sequestered into a mineral product form.

In some embodiments, some or all of the hydrogen chloride of step (a) is admixed with water to form hydrochloric acid.

In some embodiments, some or all of the magnesium hydroxide, magnesium oxide and/or MgCl(OH) of step (b)(i) is obtained from step (a)(i).

In some embodiments, some of all the water in step (a) is present in the form of a hydrate of the magnesium chloride salt.

In some embodiments, step (a) occurs in one, two or three reactors.

In some embodiments, the magnesium hydroxide, magnesium oxide and/or MgCl(OH) of step (a)(i) is greater than 90% by weight Mg(OH)Cl (e.g., between about 90%, 95%, or 97% and 99% by weight Mg(OH)Cl). In some aspects, the magnesium chloride salt is greater than 90% by weight MgCl₂.6(H₂O) (e.g., between about 90%, 95%, or 97% and 99% by weight MgCl₂.6(H₂O)).

In some embodiments, step (d) further comprises agitating the Group 2 silicate mineral with the hydrochloric acid.

In some embodiments, some or all of the magnesium chloride salt in step (a) is obtained from step (d).

In some aspects, a method of the embodiments further comprises a separation step, wherein the silicon dioxide is removed from the Group 2 chloride salt formed in step (d).

In certain embodiments, some or all of the water of step (a) is obtained from the water of step (d).

In some embodiments, the Group 2 silicate mineral of step (d) comprises a Group 2 inosilicate. In certain aspects, the Group 2 silicate mineral of step (d) comprises CaSiO₃, MgSiO₃, olivine, serpentine, sepiolite, enstatite, diopside, and/or tremolite. In some aspects, the Group 2 silicate further comprises mineralized iron and/or manganese.

In certain aspects, step (b) of a method of the embodiments further comprises admixing CaCl₂ and water to the second admixture.

In further aspects, a method of the embodiments further comprises:

(e) admixing a magnesium chloride salt and water in a third admixture under conditions suitable to form (i) magnesium hydroxide, magnesium oxide and/or MgCl(OH) and (ii) hydrogen chloride;

(f) admixing (i) magnesium hydroxide, magnesium oxide and/or MgCl(OH), (ii) CaCl₂ and (iii) carbon dioxide produced by the source in a fourth admixture under conditions suitable to form (iv) calcium carbonate, (v) a magnesium chloride salt, and (vi) water;

(g) separating the calcium carbonate from the fourth admixture; and

(h) admixing a Group 2 silicate mineral with hydrogen chloride under conditions suitable to form a Group 2 chloride salt, water, and silicon dioxide, where some or all of the hydrogen chloride in this step is obtained from step (e), whereby the carbon dioxide is sequestered into a mineral product form.

In some embodiments, some or all of the hydrogen chloride in step (h) is obtained from step (e).

In certain aspects, a method of the embodiments further comprises:

-   -   (i) admixing (i) sodium hydroxide produced from the chlor-alkali         electrolytic cell, and (ii) the carbon dioxide produced by the         source in a fifth admixture under conditions suitable to         form (iii) sodium bicarbonate and/or sodium carbonate.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present disclosure. The invention may be better understood by reference to one of these drawings in combination with the detailed description of specific embodiments presented herein.

FIG. 1 is block diagram of a system for a Group 2 hydroxide-based process to sequester CO₂ as Group 2 carbonates according to some embodiments of the present invention.

FIG. 2 is block diagram of a system in which Mg²⁺ functions as a catalyst for the sequestration of CO₂ as calcium carbonate according to some embodiments of the present invention.

FIG. 3 is a simplified process flow diagram according to some embodiments of the processes provided herein. Shown is a Group-II hydroxide-based process, which sequesters CO₂ as limestone (composed largely of the mineral calcite, CaCO₃). The term “road salt” in this figure refers to a Group II chloride, such as CaCl₂ and/or MgCl₂, either or both of which are optionally hydrated. In embodiments comprising MgCl₂, heat may be used to drive the reaction between road salt and water (including water of hydration) to form HCl and magnesium hydroxide, Mg(OH)₂, and/or magnesium hydroxychloride, Mg(OH)Cl. In embodiments comprising CaCl₂, heat may be used to drive the reaction between road salt and water to form calcium hydroxide and HCl. The HCl is reacted with, for example, calcium inosilicate rocks (optionally ground), to form additional road salt, e.g., CaCl₂, and sand (SiO₂).

FIG. 4 is a simplified process-flow diagram corresponding to some embodiments of the present invention. Silicate rocks may be used in some embodiments of the present invention to sequester CO₂ as CaCO₃. The term “road salt” in this figure refers to a Group II chloride, such as CaCl₂ and/or MgCl₂, either or both of which are optionally hydrated. In the road salt boiler, heat may be used to drive the reaction between road salt, e.g., MgCl₂.6H₂O, and water (including water of hydration) to form HO and Group II hydroxides, oxides, and/or mixed hydroxide-chlorides, including, for example, magnesium hydroxide, Mg(OH)₂, and/or magnesium hydroxychloride, Mg(OH)Cl. In embodiments comprising CaCl₂, heat may be used to drive the reaction between road salt and water to form calcium hydroxide and HCl. The HCl may be sold or reacted with silicate rocks, e.g., inosilicates, to form additional road salt, e.g., CaCl₂, and sand (SiO₂). Ion exchange reaction between Mg²⁺ and Ca²⁺ may used, in some of these embodiments, to allow, for example, the cycling of Mg²⁺ ions.

FIG. 5 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, a 35% MgCl₂, 65% H₂O solution is heated to 536° F. (280° C.), then the stream leaves in the stream labeled “H₂O—MgOH,” which comprises a solution of MgCl₂ and solid Mg(OH)₂. Typically, when Mg(OH)Cl dissolves in water it forms Mg(OH)₂ (solid) and MgCl₂ (dissolved). Here the MgCl₂ is not used to absorb CO₂ directly, rather it is recycled. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaCO₃. Results from the simulation suggest that it is efficient to recirculate a MgCl₂ stream and then to react it with H₂O and heat to form Mg(OH)₂. One or more of the aforementioned compounds then reacts with a CaCl₂/H₂O solution and CO₂ from the flue gas to ultimately form CaCO₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to repeat the process.

FIG. 6 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaCO₃. In this embodiment, the hexahydrate is dehydrated in three separate chambers and decomposed in the fourth chamber where the HCl that is formed from the decomposition is recirculated back to the third chamber to prevent any side reactions. Reactions occurring in these chambers include the following:

1^(st) Chamber: MgCl₂•6H₂O → MgCl₂•4H₂O + 2H₂O 100° C. 2^(nd) Chamber: MgCl₂•4H₂O → MgCl₂•2H₂O + 2H₂O 125° C. 3^(rd) Chamber: MgCl₂•2H₂O → MgCl₂•H₂O + H₂O 160° C. (HCl vapor present) 4^(th) Chamber: MgCl₂•H₂O → Mg(OH)Cl + HCl 130° C. HCl recirculates to the 3^(rd) chamber. Model Preferred Chamber Reaction Temp. Temp. Range Notes 1^(st) MgCl₂•6H₂O→MgCl₂•4H₂O + 2H₂O 100° C.  90° C.-120° C. 2^(nd) MgCl₂•4H₂O→MgCl₂•2H₂O + 2H₂O 125° C. 160° C.-185° C. 3^(rd) MgCl₂•2H₂O → MgCl₂•H₂O + H₂O 160° C. 190° C.-230° C. * 4^(th) MgCl₂•H₂O → Mg(OH)Cl + HCl 130° C. 230° C.-260° C. ** * HCl Vapor Present ** HCl Vapor Recirculates to the 3^(rd) Chamber The first three reactions above may be characterized as dehydrations, while the fourth may be characterized as a decomposition. Results from this simulation, which is explained in greater detail in Example 2, indicate that at lower temperatures (130-250° C.) the decomposition of MgCl₂.6H₂O results in the formation of Mg(OH)Cl instead of MgO. The Mg(OH)Cl then reacts with H₂O to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again.

FIG. 7 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaCO₃. In this embodiment, the magnesium hexahydrate is dehydrated in two separate chambers and decomposed in a third chamber. Both dehydration and decomposition reactions occur in the third chamber. There is no recirculating HCl. Reactions occurring in these chambers include the following:

1^(st) Chamber: MgCl₂•6H₂O → MgCl₂•4H₂O + 2H₂O 100° C. 2^(nd) Chamber: MgCl₂•4H₂O → MgCl₂•2H₂O + 2H₂O 125° C. 3^(rd) Chamber: MgCl₂•2H₂O → Mg(OH)Cl + HCl + H₂O 130° C. 3^(rd) Chamber: MgCl₂•2H₂O → MgCl₂•H₂O + H₂O 130° C. Model Preferred Chamber Reaction Temp. Temp. Range Notes 1^(st) MgCl₂•6H₂O → MgCl₂•4H₂O + 2H₂O 100° C.  90° C.-120° C. 2^(nd) MgCl₂•4H₂O → MgCl₂•2H₂O + 2H₂O 125° C. 160° C.-185° C. 3^(rd) MgCl₂•2H₂O → Mg(OH)Cl + HCl + 130° C. 190° C.-230° C. * H₂O MgCl₂•2H₂O → MgCl₂•H₂O + H₂O * No recirculating HCl The first, second and fourth reactions above may be characterized as dehydrations, while the third may be characterized as a decomposition. As in the embodiment of FIG. 6, the temperatures used in this embodiment result in the formation of Mg(OH)Cl from the MgCl₂.6H₂O rather than MgO. The Mg(OH)Cl then reacts with H₂O to form MgCl₂ and Mg(OH)₂, which reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. Additional details regarding this simulation are provided in Example 3 below.

FIG. 8 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaCO₃. Results from this simulation indicate that it is efficient to heat MgCl₂.6H₂O to form MgO. The MgO then reacts with H₂O to form Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium hexahydrate is simultaneously dehydrated and decomposed in one chamber at 450° C. This is the model temperature range. The preferred range in some embodiments, is 450° C.-500° C. Thus the decomposition goes completely to MgO. The main reaction occurring in this chamber can be represented as follows:

MgCl₂•6H₂O → MgO + 5H₂O + 2HCl 450° C. Additional details regarding this simulation are provided in Example 4 below.

FIG. 9 is a process flow diagram showing parameters and results from a process simulation using Aspen Plus process software similar to the embodiment of FIG. 8 except that the MgCl₂.6H₂O is decomposed into an intermediate compound, Mg(OH)Cl at a lower temperature of 250° C. in one chamber. The Mg(OH)Cl is then dissolved in water to form MgCl₂ and Mg(OH)₂, which follows through with the same reaction with CaCl₂ and CO₂ to form CaCO₃ and MgCl₂. The main reaction occurring in this chamber can be represented as follows:

MgCl₂•6H₂O → Mg(OH)Cl + HCl + 5H₂O 250° C. The reaction was modeled at 250° C. In some embodiments, the preferred range is from 230° C. to 260° C. Additional details regarding this simulation are provided in Example 5 below.

FIG. 10 shows a graph of the mass percentage of a heated sample of MgCl₂.6H₂O. The sample's initial mass was approximately 70 mg and set at 100%. During the experiment, the sample's mass was measured while it was being thermally decomposed. The temperature was quickly ramped up to 150° C., and then slowly increased by 0.5° C. per minute. At approximately 220° C., the weight became constant, consistent with the formation of Mg(OH)Cl.

FIG. 11 shows X-ray diffraction data corresponding to the product of Example 7.

FIG. 12 shows X-ray diffraction data corresponding to the product from the reaction using Mg(OH)₂ of Example 8.

FIG. 13 shows X-ray diffraction data corresponding to the product from the reaction using Mg(OH)Cl of Example 8.

FIG. 14 shows the effect of temperature and pressure on the decomposition of MgCl₂.(H₂O).

FIG. 15 is a process flow diagram of an embodiment of the Ca/Mg process described herein.

FIG. 16 is a process flow diagram of a variant of the process, whereby only magnesium compounds are used. In this embodiment the Ca²⁺—Mg²⁺ switching reaction does not occur.

FIG. 17 is a process flow diagram of a different variant of the process which is in between the previous two embodiments. Half of the Mg²⁺ is replaced by Ca²⁺, thereby making the resulting mineralized carbonate MgCa(CO₃)₂ or dolomite.

FIG. 18—CaSiO₃—Mg(OH)Cl Process, Cases 10 & 11. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, CaSiO₃, CO₂ and water, to form SiO₂ and CaCO₃. Results from this simulation indicate that it is efficient to use heat from the HCl reacting with CaSiO₃ and heat from the flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂.6H₂O to form Mg(OH)Cl. The Mg(OH)Cl then reacts with H₂O to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride hexahydrate is dehydrated to magnesium chloride dihydrate MgCl₂.2H₂O in the first chamber using heat from the HCl and CaSiO₃ reaction and decomposed in a second chamber at 250° C. using heat from the flue gas. Thus the decomposition goes partially to Mg(OH)Cl. The main reactions occurring in this chamber can be represented as follows:

ΔH** Reaction Reaction kJ/mole Temp. Range MgCl₂•6H₂O → Mg(OH)Cl + 5H₂O + HCl 433 230° C.-260° C. 2HCl(g) + CaSiO₃ → CaCl₂(aq) + H2O + −259  90° C.-150° C. SiO₂↓ 2Mg(OH)Cl + CO₂ + CaCl₂ → 2MgCl₂ + −266  25° C.-95° C. CaCO₃↓ + H₂O **Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 10 and 11 below.

FIG. 19—CaSiO₃—MgO Process, Cases 12 & 13. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, CaSiO₃, CO₂ and water, to form SiO₂ and CaCO₃. Results from this simulation indicate that it is efficient to use heat from the HCl reacting with CaSiO₃ and heat from flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂.6H₂O to form MgO. The MgO then reacts with H₂O to form Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride hexahydrate is dehydrated to magnesium chloride dihydrate MgCl₂.2H₂O in the first chamber using heat from the HCl and CaSiO₃ reaction and decomposed in a second chamber at 450° C. using heat from the flue gas. Thus the decomposition goes completely to MgO. The main reactions occurring in this chamber can be represented as follows:

Reaction Temp. Reaction ΔH kJ/mole** Range MgCl₂•6H₂O → MgO + 5H₂O + 2HCl 560 450° C.-500° C. 2HCl(g) + CaSiO₃ → CaCl₂(aq) + H₂O + −264  90° C.-150° C. SiO₂↓ MgO + CO₂ + CaCl₂(aq) → MgCl₂(aq) + −133  25° C.-95° C. CaCO₃↓ **Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 12 and 13 below.

FIG. 20—MgSiO₃—Mg(OH)Cl Process, Cases 14 & 15. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, MgSiO₃, CO₂ and water, to form SiO₂ and MgCO₃. Results from this simulation indicate that it is efficient to use heat from the HCl reacting with MgSiO₃ and heat from the flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂.2H₂O to form Mg(OH)Cl. The Mg(OH)Cl then reacts with H₂O to form MgCl₂ and Mg(OH)₂, which then reacts with CO₂ from the flue gas to form MgCO₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride remains in the dihydrate form MgCl₂.2H₂O due to the heat from the HCl and MgSiO₃ prior to decomposition at 250° C. using heat from the flue gas. Thus the decomposition goes partially to Mg(OH)Cl. The main reactions occurring in this chamber can be represented as follows:

ΔH kJ/mole Reaction Temp. Reaction ** Ranges MgCl₂•2H₂O → Mg(OH)Cl + H₂O(g) + 139.8 230° C.-260° C. HCl(g) 2HCl(g) + MgSiO₃ → MgCl₂ + H₂O + −282.8  90° C.-150° C. SiO₂↓ 2Mg(OH)Cl + CO₂ → MgCl₂ + MgCO₃↓ + −193.1  25° C.-95° C. H₂O **Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 14 and 15 below.

FIG. 21—MgSiO₃—MgO Process, Cases 16 & 17. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, MgSiO₃, CO₂ and water, to form SiO₂ and MgCO₃. Results from this simulation indicate that it is efficient to use heat from the HCl reacting with MgSiO₃ and heat from the flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂.2H₂O to form MgO. The MgO then reacts with H₂O to form Mg(OH)₂, which then reacts with CO₂ from the flue gas to form MgCO₃, which is filtered out of the stream. In this embodiment, the magnesium chloride remains in the dihydrate form MgCl₂.2H₂O due to the heat from the HCl and MgSiO₃ prior to decomposition at 450° C. using heat from the flue gas. Thus the decomposition goes completely to MgO. The main reactions occurring in this chamber can be represented as follows:

ΔH kJ/mole Reaction Temp. Reaction ** Range MgCl₂•2H₂O → MgO + H₂O(g) + 2HCl(g) 232.9 450° C.-500° C. 2HCl(g) + MgSiO₃ → MgCl₂(aq) + −293.5  90° C.-150° C. H₂O(g) + SiO₂↓ MgO + CO₂ → MgCO₃↓ −100  25° C.-95° C. **Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 16 and 17 below.

FIG. 22—Diopside-Mg(OH)Cl Process, Cases 18 & 19. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, diopside MgCa(SiO₃)₂, CO₂ and water, to form SiO₂ and dolomite MgCa(CO₃)₂. Results from this simulation indicate that it is efficient to use heat from the HCl reacting with MgCa(SiO₃)₂ and heat from the flue gas emitted by a natural gas or coal fired power plant to carry out the decomposition of MgCl₂.6H₂O to form Mg(OH)Cl. The Mg(OH)Cl then reacts with H₂O to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form MgCa(CO₃)₂ which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride hexahydrate is dehydrated to magnesium chloride dihydrate MgCl₂.2H₂O in the first chamber using heat from the HCl and CaSiO₃ reaction and decomposed to Mg(OH)Cl in a second chamber at 250° C. using heat from the flue gas. The main reactions occurring in this chamber can be represented as follows:

ΔH Reaction Reaction kJ/mole** Temp. Range MgCl₂•6H₂O → Mg(OH)Cl + 5H₂O(g) + 433 230° C.-260° C. HCl(g) 2HCl(g) + MgCa(SiO₃)₂ → CaCl₂(aq) + −235  90° C.-150° C. MgSiO₃↓ + SiO₂↓ + H₂O 2HCl(g) + MgSiO₃ → MgCl₂(aq) + −282.8  90° C.-150° C. SiO₂↓ + H₂O 4Mg(OH)Cl + 2CO₂ + CaCl₂(aq) → −442  25° C.-95° C. MgCa(CO₃)₂↓ + 3MgCl₂(aq) + 2H₂O **Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 18 and 19 below.

FIG. 23—Diopside-MgO Process, Cases 20 & 21. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. The net reaction is the capture of CO₂ from flue gas using inexpensive raw materials, diopside MgCa(SiO₃)₂, CO₂ and water, to form SiO₂ and dolomite MgCa(CO₃)₂. Results from this simulation indicate that it is efficient to use heat from the HCl reacting with MgCa(SiO₃)₂ and heat from the flue gas emitted by a natural gas or coal fired power plant and/or other heat source to carry out the decomposition of MgCl₂.6H₂O to form MgO. The MgO then reacts with H₂O to form Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form MgCa(CO₃)₂ which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. In this embodiment, the magnesium chloride hexahydrate is dehydrated to magnesium chloride dihydrate MgCl₂.2H₂O in the first chamber using heat from the HCl and CaSiO₃ reaction and decomposed to MgO in a second chamber at 450° C. using heat from the flue gas. The main reactions occurring in this chamber can be represented as follows:

Reaction ΔH Temp. Reaction kJ/mole** Range MgCl₂•6H₂O → MgO + 5H₂O + 2HCl 560 450° C.-500° C. 2HCl(g) + MgCa(SiO₃)₂ → −240  90° C.-150° C. CaCl₂(g) + MgSiO₃↓ + SiO₂↓ + H₂O 2HCl(aq) + MgSiO₃ → MgCl₂(aq) + −288  90° C.-150° C. SiO₂↓ + H₂O 2MgO + 2CO₂ + CaCl₂(aq) → −258  25° C.-95° C. MgCa(CO₃)₂↓ + MgCl₂(aq) **Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Additional details regarding this simulation are provided in Examples 20 and 21 below.

FIG. 24 illustrates the percent CO₂ captured for varying CO₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and also whether the process relied on full or partial decomposition. See Examples 10 through 13 of the CaSiO₃—Mg(OH)Cl and CaSiO₃—MgO processes.

FIG. 25 illustrates the percent CO₂ captured for varying CO₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and also whether the process relied on full or partial decomposition. See Examples 14 through 17 of the MgSiO₃—Mg(OH)Cl and MgSiO₃—MgO processes.

FIG. 26 illustrates the percent CO₂ captured for varying CO₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and also whether the process relied on full or partial decomposition. See Examples 18 through 21 of the Diopside-Mg(OH)Cl and Diopside-MgO processes.

FIG. 27 is a simplified process-flow diagram corresponding to some embodiments of the present invention in which two different salts, e.g., Ca²⁺ and Mg²⁺, are used for decomposition and carbonation.

FIGS. 28-29 show graphs of the mass percentages of heated samples of MgCl₂.6H₂O. The initial masses of the samples were approximately 70 mg each and were each set at 100%. During the experiment, the masses of the samples were measured while they was being thermally decomposed. The temperature was ramped up to 200° C. then further increased over the course of a 12 hour run. The identities of the decomposed materials can be confirmed by comparing against the theoretical plateaus provided. FIG. 28 is a superposition of two plots, the first one being the solid line, which is a plot of time (minutes) versus temperature (° C.). The line illustrates the ramping of temperature over time; the second plot, being the dashed line is a plot of weight % (100%=original weight of sample) versus time, which illustrates the reduction of the sample's weight over time whether by dehydration or decomposition. FIG. 29 is also a superposition of two plots, the first (the solid line) is a plot of weight % versus temperature (° C.), illustrating the sample's weight decreasing as the temperature increases; the second plot (the dashed line) is a plot of the derivative of the weight % with respect to temperature (wt. %/° C.) versus temperature ° C. When this value is high it indicates a higher rate of weight loss for each change per degree. If this value is zero, the sample's weight remains the same although the temperature is increasing, indicating an absence of dehydration or decomposition. Note FIGS. 28 and 29 are of the same sample.

FIG. 30—MgCl₂.6H₂O Decomposition at 500° C. after One Hour. This graph shows the normalized final and initial weights of four test runs of MgCl₂.6H₂O after heating at 500° C. for one hour. The consistent final weight confirms that MgO is made by decomposition at this temperature.

FIG. 31—Three-Chamber Decomposition. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, heat from cold flue gas (chamber 1), heat from mineral dissolution reactor (chamber 2), and external natural gas (chamber 3) are used as heat sources. This process flow diagram illustrates a three chamber process for the decomposition to Mg(OH)Cl. The first chamber is heated by 200° C. flue gas to provide some initial heat about ˜8.2% of the total required heat, the second chamber which relies on heat recovered from the mineral dissolution reactor to provide 83% of the needed heat for the decomposition of which 28% is from the hydrochloric acid/mineral silicate reaction and 55% is from the condensation and formation of hydrochloric acid, and finally the third chamber, which uses natural gas as an external source of the remaining heat which is 8.5% of the total heat. The CO₂ is from a combined cycle power natural gas plant, so very little heat is available from the power plant to power the decomposition reaction.

FIG. 32—Four-Chamber Decomposition. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, heat from cold flue gas (chamber 1), heat from additional steam (chamber 2), heat from mineral dissolution reactor (chamber 3), and external natural gas (chamber 4) are used as heat sources. This process flow diagram illustrates a four chamber process for the decomposition to Mg(OH)Cl, the first chamber provides 200° C. flue gas to provide some initial heat about ˜8.2% of the total required heat, the second chamber provides heat in the form of extra steam which is 0.8% of the total heat needed, the third chamber which relies on heat recovered from the mineral dissolution reactor to provide 83% of the needed heat for the decomposition of which 28% is from the hydrochloric acid/mineral silicate reaction and 55% is from the condensation and formation of hydrochloric acid, and finally the fourth chamber, which uses natural gas as an external source of the remaining heat which is 8.0% of the total heat. The CO₂ is from a combined cycle natural gas power plant, so very little heat is available from the power plant to power the decomposition reaction.

FIG. 33—Two-Chamber Decomposition. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, heat from mineral dissolution reactor (chamber 1), and external natural gas (chamber 2) are used as heat sources. This process flow diagram illustrates a two chamber process for the decomposition to Mg(OH)Cl, the first chamber which relies on heat recovered from the mineral dissolution reactor to provide 87% of the needed heat for the decomposition of which 28% is from the hydrochloric acid/mineral silicate reaction and 59% is from the condensation and formation of hydrochloric acid, and the second chamber, which uses natural gas as an external source of the remaining heat which is 13% of the total heat. The CO₂ is from a combined cycle natural gas power plant, so very little heat is available from the power plant to power the decomposition reaction.

FIG. 34—Two-Chamber Decomposition. This figure shows a process flow diagram providing parameters and results from a process simulation using Aspen Plus process software. In this embodiment, heat from mineral dissolution reactor (chamber 1), and hot flue gas from open cycle natural gas plant (chamber 2) are used as heat sources. This process flow diagram illustrates a two chamber process for the decomposition to Mg(OH)Cl, the first chamber which relies on heat recovered from the mineral dissolution reactor to provide 87% of the needed heat for the decomposition of which 28% is from the hydrochloric acid/mineral silicate reaction and 59% is from the condensation and formation of hydrochloric acid, and the second chamber, which uses hot flue gas as an external source of the remaining heat which is 13% of the total heat. The CO₂ is from an open cycle natural gas power plant, therefore substantial heat is available from the power plant in the form of 600° C. flue gas to power the decomposition reaction.

FIG. 35 shows a schematic diagram of a Auger reactor which may be used for the salt decomposition reaction, including the decomposition of MgCl₂.6H₂O to M(OH)Cl or MgO. Such reactors may comprises internal heating for efficient heat utilization, external insulation for efficient heat utilization, a screw mechanism for adequate solid transport (when solid is present), adequate venting for HCl removal. Such a reactors has been used to prepare ˜1.8 kg of ˜90% Mg(OH)Cl.

FIG. 36 shows the optimization index for two separate runs of making Mg(OH)Cl using an Auger reactor. The optimization index=% conversion×% efficiency.

FIG. 37 shows a process flow diagram of an Aspen model that simulates an CaSiO₃—Mg(OH)Cl Process.

FIG. 38 is a block diagram of a system according to embodiments of the present invention. DC1, DC2 and DC3 are three separate sources of electrical energy.

FIG. 39 is a block diagram of a system according to embodiments of the present invention.

FIG. 40 shows CO2 captured versus % CO2 in stack gas, stack gas temperature and type of stack gas, e.g. derived from coal or natural gas.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention relates to carbon dioxide sequestration, including energy-efficient processes in which Group 2 chlorides are converted to Group 2 hydroxides and hydrogen chloride, which are then used to remove carbon dioxide from waste streams. In some embodiments, hydrogen chloride may be further reacted with Group 2 silicates to produce additional Group 2 chloride starting materials and silica.

In some embodiments, the methods and apparatuses of the invention comprise one or more of the following general components: (1) the conversion of Group 2 silicate minerals with hydrogen chloride into Group 2 chlorides and silicon dioxide, (2) conversion of Group 2 chlorides into Group 2 hydroxides and hydrogen chloride, (3) an aqueous decarbonation whereby gaseous CO₂ is absorbed into an aqueous caustic mixture comprising Group 2 hydroxides to form Group 2 carbonate and/or bicarbonate products and water, (4) a separation process whereby the carbonate and/or bicarbonate products are separated from the liquid mixture, (5) the reuse or cycling of by-products, including energy, from one or more of the steps or process streams into another one or more steps or process streams. Each of these general components is explained in further detail below.

While many embodiments of the present invention consume some energy to accomplish the absorption of CO₂ and other chemicals from flue-gas streams and to accomplish the other objectives of embodiments of the present invention as described herein, one advantage of certain embodiments of the present invention is that they provide ecological efficiencies that are superior to those of the prior art, while absorbing most or all of the emitted CO₂ from a given source, such as a power plant.

Another additional benefit of certain embodiments of the present invention that distinguishes them from other CO₂-removal processes is that in some market conditions, the products are worth considerably more than the reactants required or the net-power or plant-depreciation costs. In other words, certain embodiments are industrial methods of producing chloro-hydro-carbonate products at a profit, while accomplishing considerable removal of CO₂ and incidental pollutants of concern.

Other objects, features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

I. DEFINITIONS

As used herein, the terms “carbonates” or “carbonate products” are generally defined as mineral components containing the carbonate group, [CO₃]²⁻. Thus, the terms encompass both carbonate/bicarbonate mixtures and species containing solely the carbonate ion. The terms “bicarbonates” and “bicarbonate products” are generally defined as mineral components containing the bicarbonate group, [HCO₃]¹⁻. Thus, the terms encompass both carbonate/bicarbonate mixtures and species containing solely the bicarbonate ion.

As used herein “Ca/Mg” signifies either Ca alone, Mg alone or a mixture of both Ca and Mg. The ratio of Ca to Mg may range from 0:100 to 100:0, including, e.g., 1:99, 5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, 95:5, and 99:1. The symbols “Ca/Mg”, “MgxCa(1−x)” and CaxMg(1−x)” are synonymous. In contrast, “CaMg” or “MgCa” refers to a 1:1 ratio of these two ions.

As used herein, the term “ecological efficiency” is used synonymously with the term “thermodynamic efficiency” and is defined as the amount of CO₂ sequestered by certain embodiments of the present invention per energy consumed (represented by the equation “∂CO₂/∂E”), appropriate units for this value are kWh/ton CO₂. CO₂ sequestration is denominated in terms of percent of total plant CO₂; energy consumption is similarly denominated in terms of total plant power consumption.

The terms “Group II” and “Group 2” are used interchangeably.

“Hexahydrate” refers to MgCl₂.6H₂O.

In the formation of bicarbonates and carbonates using some embodiments of the present invention, the term “ion ratio” refers to the ratio of cations in the product divided by the number of carbons present in that product. Hence, a product stream formed of calcium bicarbonate (Ca(HCO₃)₂) may be said to have an “ion ratio” of 0.5 (Ca/C), whereas a product stream formed of pure calcium carbonate (CaCO₃) may be said to have an “ion ratio” of 1.0 (Ca/C). By extension, an infinite number of continuous mixtures of carbonate and bicarbonate of mono-, di- and trivalent cations may be said to have ion ratios varying between 0.5 and 3.0.

Based on the context, the abbreviation “MW” either means molecular weight or megawatts.

The abbreviation “PFD” is process flow diagram.

The abbreviation “Q” is heat (or heat duty), and heat is a type of energy. This does not include any other types of energy.

As used herein, the term “sequestration” is used to refer generally to techniques or practices whose partial or whole effect is to remove CO₂ from point emissions sources and to store that CO₂ in some form so as to prevent its return to the atmosphere. Use of this term does not exclude any form of the described embodiments from being considered “sequestration” techniques.

In the context of a chemical formula, the abbreviation “W” refers to H₂O.

The pyroxenes are a group of silicate minerals found in many igneous and metamorphic rocks. They share a common structure consisting of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems. Pyroxenes have the general formula XY(Si,Al)₂O₆, where X represents calcium, sodium, iron (II) and magnesium and more rarely zinc, manganese and lithium and Y represents ions of smaller size, such as chromium, aluminium, iron(III), magnesium, manganese, scandium, titanium, vanadium and even iron (II).

In addition, atoms making up the compounds of the present invention are intended to include all isotopic forms of such atoms. Isotopes, as used herein, include those atoms having the same atomic number but different mass numbers. By way of general example and without limitation, isotopes of hydrogen include tritium and deuterium, and isotopes of carbon include ¹³C and ¹⁴C.

The use of the word “a” or “an,” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.”

Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects.

The terms “comprise,” “have” and “include” are open-ended linking verbs. Any forms or tenses of one or more of these verbs, such as “comprises,” “comprising,” “has,” “having,” “includes” and “including,” are also open-ended. For example, any method that “comprises,” “has” or “includes” one or more steps is not limited to possessing only those one or more steps and also covers other unlisted steps.

The term “effective,” as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.

The above definitions supersede any conflicting definition in any of the reference that is incorporated by reference herein. The fact that certain terms are defined, however, should not be considered as indicative that any term that is undefined is indefinite. Rather, all terms used are believed to describe the invention in terms such that one of ordinary skill can appreciate the scope and practice the present invention.

II. SEQUESTRATION OF CARBON DIOXIDE USING SALTS OF GROUP II METALS

FIG. 1 depicts a simplified process-flow diagram illustrating general, exemplary embodiments of the apparatuses and methods of the present disclosure. This diagram is offered for illustrative purposes only, and thus it merely depicts specific embodiments of the present invention and is not intended to limit the scope of the claims in any way.

In the embodiment shown in FIG. 1, reactor 10 (e.g., a road salt boiler) uses power, such as external power and/or recaptured power (e.g., heat from hot flue gas or an external source of heat such as solar concentration or combustion), to drive a reaction represented by equation 1. (Ca/Mg)Cl₂+2H₂O→(Ca/Mg)(OH)₂+2HCl  (1) The water used in this reaction may be in the form of liquid, steam, a crystalline hydrate, e.g., MgCl₂.6H₂O, CaCl₂.2H₂O, or it may be supercritical. In some embodiments, the reaction uses MgCl₂ to form Mg(OH)₂ and/or Mg(OH)Cl (see, e.g., FIG. 2). In some embodiments, the reaction uses CaCl₂ to form Ca(OH)₂. Some or all of the Group 2 hydroxide or hydroxychloride (not shown) from equation 1 may be delivered to reactor 20. In some embodiments, some or all of the Group 2 hydroxide and/or Group 2 hydroxychloride is delivered to reactor 20 as an aqueous solution. In some embodiments, some or all of the Group 2 hydroxide is delivered to reactor 20 in an aqueous suspension. In some embodiments, some or all of the Group 2 hydroxide is delivered to reactor 20 as a solid. In some embodiments, some or all of the hydrogen chloride (e.g., in the form of vapor or in the form of hydrochloric acid) may be delivered to reactor 30 (e.g., a rock melter). In some embodiments, the resulting Group 2 hydroxides are further heated to remove water and form corresponding Group 2 oxides. In some variants, some or all of these Group 2 oxides may then be delivered to reactor 20.

Carbon dioxide from a source, e.g., flue-gas, enters the process at reactor 20 (e.g., a fluidized bed reactor, a spray-tower decarbonator or a decarbonation bubbler), potentially after initially exchanging waste-heat with a waste-heat/DC generation system. In some embodiments the temperature of the flue gas is at least 125° C. The Group 2 hydroxide, some or all of which may be obtained from reactor 10, reacts with carbon dioxide in reactor 20 according to the reaction represented by equation 2. (Ca/Mg)(OH)₂+CO₂→(Ca/Mg)CO₃+H₂O  (2) The water produced from this reaction may be delivered back to reactor 10. The Group 2 carbonate is typically separated from the reaction mixture. Group 2 carbonates have a very low K_(sp) (solubility product constant). So they be separated as solids from other, more soluble compounds that can be kept in solution. In some embodiments, the reaction proceeds through Group 2 bicarbonate salts. In some embodiments, Group 2 bicarbonate salts are generated and optionally then separated from the reaction mixture. In some embodiments, Group 2 oxides, optionally together with or separately from the Group 2 hydroxides, are reacted with carbon dioxide to also form Group 2 carbonate salts. In some embodiments, the flue gas, from which CO₂ and/or other pollutants have been removed, is released to the air.

Group 2 silicates (e.g., CaSiO₃, MgSiO₃, MgO.Fe.SiO₂, etc.) enter the process at reactor 30 (e.g., a rock melter or a mineral dissociation reactor). In some embodiments, these Group 2 silicates are ground in a prior step. In some embodiments, the Group 2 silicates are inosilicates. These minerals may be reacted with hydrochloric acid, either as a gas or in the form of hydrochloric acid, some or all of which may be obtained from reactor 10, to form the corresponding Group 2 metal chlorides (CaCl₂ and/or MgCl₂), water and sand (SiO₂). The reaction can be represented by equation 3. 2HCl+(Ca/Mg)SiO₃→(Ca/Mg)Cl₂+H₂O+SiO₂  (3) Some or all of the water produced from this reaction may be delivered to reactor 10. Some or all of the Group 2 chlorides from equation 3 may be delivered to reactor 20. In some embodiments, some or all of the Group 2 chloride is delivered to reactor 20 as an aqueous solution. In some embodiments, some or all of the Group 2 chloride is delivered to reactor 20 in an aqueous suspension. In some embodiments, some or all of the Group 2 chloride is delivered to reactor 20 as a solid.

The net reaction capturing the summation of equations 1-3 is shown here as equation 4: CO₂+(Ca/Mg)SiO₃→(Ca/Mg)CO₃+SiO₂  (4)

In another embodiment, the resulting Mg_(x)Ca_((1-x))CO₃ sequestrant is reacted with HCl in a manner to regenerate and concentrate the CO₂. The Ca/MgCl₂ thus formed is returned to the decomposition reactor to produce CO₂ absorbing hydroxides or hydroxyhalides.

Through the process shown in FIG. 1 and described herein, Group 2 carbonates are generated as end-sequestrant material from the captured CO₂. Some or all of the water, hydrogen chloride and/or reaction energy may be cycled. In some embodiments, only some or none of these are cycled. In some embodiments, the water, hydrogen chloride and reaction energy made be used for other purposes.

In some embodiments, and depending on the concentration of CO₂ in the flue gas stream of a given plant, the methods disclosed herein may be used to capture 33-66% of the plant's CO₂ using heat-only as the driver (no electrical penalty). In some embodiments, the efficiencies of the methods disclosed herein improve with lower CO₂-concentrations, and increase with higher (unscrubbed) flue-gas temperatures. For example, at 320° C. and 7% CO₂ concentration, 33% of flue-gas CO₂ can be mineralized from waste-heat alone. In other embodiments, e.g., at the exit temperatures of natural gas turbines approximately 100% mineralization can be achieved.

These methods and devices can be further modified, e.g., with modular components, optimized and scaled up using the principles and techniques of chemistry, chemical engineering, and/or materials science as applied by a person skilled in the art. Such principles and techniques are taught, for example, in U.S. Pat. No. 7,727,374, U.S. Patent Application Publications 2006/0185985 and 2009/0127127, U.S. patent application Ser. No. 11/233,509, filed Sep. 22, 2005, U.S. Provisional Patent Application No. 60/718,906, filed Sep. 20, 2005; U.S. Provisional Patent Application No. 60/642,698, filed Jan. 10, 2005; U.S. Provisional Patent Application No. 60/612,355, filed Sep. 23, 2004, U.S. patent application Ser. No. 12/235,482, filed Sep. 22, 2008, U.S. Provisional Application No. 60/973,948, filed Sep. 20, 2007, U.S. Provisional Application No. 61/032,802, filed Feb. 29, 2008, U.S. Provisional Application No. 61/033,298, filed Mar. 3, 2008, U.S. Provisional Application No. 61/288,242, filed Jan. 20, 2010, U.S. Provisional Application No. 61/362,607, filed Jul. 8, 2010, and International Application No. PCT/US08/77122, filed Sep. 19, 2008. The entire text of each of the above-referenced disclosures (including any appendices) is specifically incorporated by reference herein.

The above examples were included to demonstrate particular embodiments of the invention. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

III. SEQUESTRATION OF CARBON DIOXIDE USING MG²⁺ AS CATALYST

FIG. 2 depicts a simplified process-flow diagram illustrating general, exemplary embodiments of the apparatuses and methods of the present disclosure. This diagram is offered for illustrative purposes only, and thus it merely depicts specific embodiments of the present invention and is not intended to limit the scope of the claims in any way.

In the embodiment shown in FIG. 2, reactor 100 uses power, such as external power and/or recaptured power (e.g., heat from hot flue gas), to drive a decomposition-type reaction represented by equation 5. MgCl₂ .x(H₂O)+yH₂O→z′[Mg(OH)₂ ]+z″[MgO]+z′″[MgCl(OH)]+(2z′+2z″+z′″)[HCl]  (5) The water used in this reaction may be in the form of a hydrate of magnesium chloride, liquid, steam and/or it may be supercritical. In some embodiments, the reaction may occur in one, two, three or more reactors. In some embodiments, the reaction may occur as a batch, semi-batch of continuous process. In some embodiments, some or all of the magnesium salt product may be delivered to reactor 200. In some embodiments, some or all of the magnesium salt product is delivered to reactor 200 as an aqueous solution. In some embodiments, some or all of the magnesium salt product is delivered to reactor 200 in an aqueous suspension. In some embodiments, some or all of the magnesium salt product is delivered to reactor 200 as a solid. In some embodiments, some or all of the hydrogen chloride (e.g., in the form of vapor or in the form of hydrochloric acid) may be delivered to reactor 300 (e.g., a rock melter). In some embodiments, the Mg(OH)₂ is further heated to remove water and form MgO. In some embodiments, the MgCl(OH) is further heated to remove HCl and form MgO. In some variants, one or more of Mg(OH)₂, MgCl(OH) and MgO may then be delivered to reactor 200.

Carbon dioxide from a source, e.g., flue-gas, enters the process at reactor 200 (e.g., a fluidized bed reactor, a spray-tower decarbonator or a decarbonation bubbler), potentially after initially exchanging waste-heat with a waste-heat/DC generation system. In some embodiments the temperature of the flue gas is at least 125° C. Admixed with the carbon dioxide is the magnesium salt product from reactor 100 and CaCl₂ (e.g., rock salt). The carbon dioxide reacts with the magnesium salt product and CaCl₂ in reactor 200 according to the reaction represented by equation 6. CO₂+CaCl₂ +z′[Mg(OH)₂ ]+z″[MgO]+z′″[MgCl(OH)]→(z′+z″+z′″)MgCl₂+(z′+½z′″)H₂O+CaCO₃  (6) In some embodiments, the water produced from this reaction may be delivered back to reactor 100. The calcium carbonate product (e.g., limestone, calcite) is typically separated (e.g., through precipitation) from the reaction mixture. In some embodiments, the reaction proceeds through magnesium carbonate and bicarbonate salts. In some embodiments, the reaction proceeds through calcium bicarbonate salts. In some embodiments, various Group 2 bicarbonate salts are generated and optionally then separated from the reaction mixture. In some embodiments, the flue gas, from which CO₂ and/or other pollutants have been removed, is released to the air, optionally after one or more further purification and/or treatment steps. In some embodiments, the MgCl₂ product, optionally hydrated, is returned to reactor 100. In some embodiments, the MgCl₂ product is subjected to one or more isolation, purification and/or hydration steps before being returned to reactor 100.

Calcium silicate (e.g., 3CaO.SiO₂, Ca₃SiO₅; 2CaO.SiO₂, Ca₂SiO₄; 3CaO.2SiO₂, Ca₃Si₂O₇ and CaO.SiO₂, CaSiO₃ enters the process at reactor 300 (e.g., a rock melter). In some embodiments, these Group 2 silicates are ground in a prior step. In some embodiments, the Group 2 silicates are inosilicates. In the embodiment of FIG. 2, the inosilicate is CaSiO₃ (e.g., wollastonite, which may itself, in some embodiments, contain small amounts of iron, magnesium and/or manganese substituting for iron). The CaSiO₃ is reacted with hydrogen chloride, either gas or in the form of hydrochloric acid, some or all of which may be obtained from reactor 100, to form CaCl₂, water and sand (SiO₂). The reaction can be represented by equation 7. 2HCl+(Ca/Mg)SiO₃→(Ca/Mg)Cl₂+H₂O+SiO₂  (7)

Reaction ΔH Temp. Reaction kJ/mole** Range 2 HCl(g) + CaSiO₃ → CaCl₂ + H₂O + SiO₂ −254 90° C.-150° C. 2 HCl(g) + MgSiO₃ → MgCl₂(aq) + −288 90° C.-150° C. H₂O + SiO₂ **Enthalpies are based on reaction temperatures, and temperatures of incoming reactant and outgoing product streams. Some or all of the water produced from this reaction may be delivered to reactor 100. Some or all of the CaCl₂ from equation 7 may be delivered to reactor 200. In some embodiments, some or all of the CaCl₂ is delivered to reactor 200 as an aqueous solution. In some embodiments, some or all of the CaCl₂ is delivered to reactor 200 in an aqueous suspension. In some embodiments, some or all of the CaCl₂ is delivered to reactor 200 as a solid.

The net reaction capturing the summation of equations 5-7 is shown here as equation 8: CO₂+CaSiO₃→CaCO₃+SiO₂  (8)

Reaction ΔH kJ/mole** ΔG kJ/mole** CO₂ + CaSiO₃ → CaCO₃ + SiO₂ −89 −39 **Measured at standard temperature and pressure (STP). Through the process shown in FIG. 2 and described herein, calcium carbonates are generated as end-sequestrant material from CO₂ and calcium inosilicate. Some or all of the various magnesium salts, water, hydrogen chloride and reaction energy may be cycled. In some embodiments, only some or none of these are cycled. In some embodiments, the water, hydrogen chloride and/or reaction energy made be used for other purposes.

These methods and devices can be further modified, optimized and scaled up using the principles and techniques of chemistry, chemical engineering, and/or materials science as applied by a person skilled in the art. Such principles and techniques are taught, for example, in U.S. Pat. No. 7,727,374, U.S. Patent Application Publications 2006/0185985 and 2009/0127127, U.S. patent application Ser. No. 11/233,509, filed Sep. 22, 2005, U.S. Provisional Patent Application No. 60/718,906, filed Sep. 20, 2005; U.S. Provisional Patent Application No. 60/642,698, filed Jan. 10, 2005; U.S. Provisional Patent Application No. 60/612,355, filed Sep. 23, 2004, U.S. patent application Ser. No. 12/235,482, filed Sep. 22, 2008, U.S. Provisional Application No. 60/973,948, filed Sep. 20, 2007, U.S. Provisional Application No. 61/032,802, filed Feb. 29, 2008, U.S. Provisional Application No. 61/033,298, filed Mar. 3, 2008, U.S. Provisional Application No. 61/288,242, filed Jan. 20, 2010, U.S. Provisional Application No. 61/362,607, filed Jul. 8, 2010, and International Application No. PCT/US08/77122, filed Sep. 19, 2008. The entire text of each of the above-referenced disclosures (including any appendices) is specifically incorporated by reference herein.

The above examples were included to demonstrate particular embodiments of the invention. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

IV. CONVERSION OF GROUP 2 CHLORIDES INTO GROUP 2 HYDROXIDES OR GROUP II HYDROXY CHLORIDES

Disclosed herein are processes that react a Group 2 chloride, e.g., CaCl₂ or MgCl₂, with water to form a Group 2 hydroxide, a Group 2 oxide, and/or a mixed salt such as a Group 2 hydroxide chloride. Such reactions are typically referred to as decompositions. In some embodiments, the water may be in the form of liquid, steam, from a hydrate of the Group 2 chloride, and/or it may be supercritical. The steam may come from a heat exchanger whereby heat from an immensely combustible reaction, i.e. natural gas and oxygen or hydrogen and chlorine heats a stream of water. In some embodiments, steam may also be generated through the use of plant or factory waste heat. In some embodiments, the chloride salt, anhydrous or hydrated, is also heated.

In the case of Mg²⁺ and Ca²⁺, the reactions may be represented by equations 9 and 10, respectively: MgCl₂+2H₂O→Mg(OH)₂+2HCl(g) ΔH=263 kJ/mole**  (9) CaCl₂+2H₂O→Ca(OH)₂+2HCl(g) ΔH=284 kJ/mole**  (10) **Measured at 100° C. The reactions are endothermic meaning energy, e.g., heat has to be applied to make these reactions occur. Such energy may be obtained from the waste-heat generated from one or more of the exothermic process steps disclosed herein. The above reactions may occur according to one of more of the following steps: CaCl₂+(x+y+z)H₂O→Ca²⁺ .xH₂O+Cl⁻ .yH₂O+Cl⁻ .zH₂O  (11) Ca⁺² .xH₂O+Cl⁻ .yH₂O+Cl⁻ .zH₂O→[Ca²⁺.(x−1)(H₂O)OH⁻]⁺+Cl⁻.(yH₂O)+Cl⁻.(z−1)H₂O+H₃O⁺  (12) [Ca²⁺.(x−1)(H₂O)OH⁻]⁺+Cl⁻.(yH₂O)+Cl⁻.(z−1)H₂O+H₃O⁺→[Ca²⁺.(x−1)(H₂O)OH⁻]⁺+Cl⁻.(yH₂O)⁻ +zH₂O+HCl(g)↑  (13) [Ca²⁺.(x−1)(H₂O)OH⁻]⁺+Cl⁻.(yH₂O)→[Ca²⁺.(x−2)(H₂O)(OH⁻)₂]+Cl⁻.(y−1)H₂O+H₃O⁺  (14) [Ca²⁺.(x−2)(H₂O)(OH⁻)₂]+Cl⁻.(y−1)H₂O+H₃O⁺→Ca(OH)₂↓+(x−2)H₂O+yH₂O↑  (15)

The reaction enthalpy (ΔH) for CaCl₂+2H₂O→Ca(OH)₂+2HCl(g) is 284 kJ/mole at 100° C. In some variants, the salt MgCl₂.6H₂O, magnesium hexahydrate, is used. Since water is incorporated into the molecular structure of the salt, direct heating without any additional steam or water may be used to initiate the decomposition. Typical reactions temperatures for the following reactions are shown here:

From 95-110° C.: MgCl₂.6H₂O→MgCl₂.4H₂O+2H₂O  (16) MgCl₂.4H₂O→MgCl₂.2H₂O+2H₂O  (17) From 135-180° C.: MgCl₂.4H₂O→Mg(OH)Cl+HCl+3H₂O  (18) MgCl₂.2H₂O→MgCl₂.H₂O+H₂O  (19) From 185-230° C.: MgCl₂.2H₂O→Mg(OH)Cl+HCl+H₂O  (20) From >230° C.: MgCl₂.H₂O→MgCl₂+H₂O  (21) MgCl₂.H₂O→Mg(OH)Cl+HCl  (22) Mg(OH)Cl→MgO+HCl  (23)

Referenced Temp. ΔH Temp. Reaction Range kJ/mole** Reaction MgCl₂•6H₂O → MgCl₂•4H₂O +   95° C.-110° C. 115.7 100° C. 2 H₂O(g) MgCl₂•4H₂O → MgCl₂•2H₂O +  95° C.-110° C. 134.4 100° C. 2 H₂O(g) MgCl₂•4H₂O → Mg(OH)Cl + 135° C.-180° C. 275 160° C. HCl(g) + 3 H₂O(g) MgCl₂•2H₂O → MgCl₂•H₂O + 135° C.-180° C. 70.1 160° C. H₂O(g) MgCl₂•2H₂O → Mg(OH)Cl + 185° C.-230° C. 141 210° C. HCl(g) + H₂O(g) MgCl₂•H₂O → MgCl₂ + H₂O(g) >230° C. 76.6 240° C. MgCl₂•H₂O → Mg(OH)Cl + >230° C. 70.9 240° C. HCl(g) Mg(OH)Cl → MgO + HCl(g) >230° C. 99.2 450° C. **ΔH values were calculated at the temperature of reaction (column “Temp. Reaction”). See the chemical reference Kirk Othmer 4^(th) ed. Vol. 15 p. 343 1998 John Wiley and Sons, which is incorporated herein by reference. See example 1, below, providing results from a simulation that demonstrating the ability to capture CO₂ from flue gas using an inexpensive raw material, CaCl₂, to form CaCO₃. See also Energy Requirements and Equilibrium in the dehydration, hydrolysis and decomposition of Magnesium Chloride-K.K. Kelley, Bureau of Mines 1941 and Kinetic Analysis of Thermal Dehydration and Hydrolysis of MgCl2•6H2O by DTA and TG-Y. Kirsh, S. Yariv and S. Shoval-Journal of Thermal Analysis, Vol. 32 (1987), both of which are incorporated herein by reference in their entireties.

V. REACTION OF GROUP 2 HYDROXIDES AND CO₂ TO FORM GROUP 2 CARBONATES

In another aspect of the present disclosure, there are provided apparatuses and methods for the decarbonation of carbon dioxide sources using Group 2 hydroxides, Group 2 oxides, and/or Group 2 hydroxide chlorides as CO₂ adsorbents. In some embodiments, CO₂ is absorbed into an aqueous caustic mixture and/or solution where it reacts with the hydroxide and/or oxide salts to form carbonate and bicarbonate products. Sodium hydroxide, calcium hydroxide and magnesium hydroxide, in various concentrations, are known to readily absorb CO₂. Thus, in embodiments of the present invention, Group 2 hydroxides, Group 2 oxides (such as CaO and/or MgO) and/or other hydroxides and oxides, e.g., sodium hydroxide may be used as the absorbing reagent.

For example, a Group 2 hydroxide, e.g., obtained from a Group 2 chloride, may be used in an adsorption tower to react with and thereby capture CO₂ based on one or both of the following reactions: Ca(OH)₂+CO₂→CaCO₃+H₂O  (24)

-   -   ΔH=−117.92 kJ/mol**     -   ΔG=−79.91 kJ/mol**         Mg(OH)₂+CO₂→MgCO₃+H₂O  (25)     -   ΔH=−58.85 kJ/mol**     -   ΔG=−16.57 kJ/mol** ** Calculated at STP.

In some embodiments of the present invention, most or nearly all of the carbon dioxide is reacted in this manner. In some embodiments, the reaction may be driven to completion, for example, through the removal of water, whether through continuous or discontinous processes, and/or by means of the precipitation of bicarbonate, carbonate, or a mixture of both types of salts. See example 1, below, providing a simulation demonstrating the ability to capture CO₂ from flue gas using an inexpensive raw material, Ca(CO)₂ derived from CaCl₂, to form CaCO₃.

In some embodiments, an initially formed Group 2 may undergo an salt exchange reaction with a second Group 2 hydroxide to transfer the carbonate anion. For example: CaCl₂+MgCO₃+→MgCl₂+CaCO₃  (25a)

These methods and devices can be further modified, optimized and scaled up using the principles and techniques of chemistry, chemical engineering, and/or materials science as applied by a person skilled in the art. Such principles and techniques are taught, for example, in U.S. Pat. No. 7,727,374, U.S. patent application Ser. No. 11/233,509, filed Sep. 22, 2005, U.S. Provisional Patent Application No. 60/718,906, filed Sep. 20, 2005; U.S. Provisional Patent Application No. 60/642,698, filed Jan. 10, 2005; U.S. Provisional Patent Application No. 60/612,355, filed Sep. 23, 2004, U.S. patent application Ser. No. 12/235,482, filed Sep. 22, 2008, U.S. Provisional Application No. 60/973,948, filed Sep. 20, 2007, U.S. Provisional Application No. 61/032,802, filed Feb. 29, 2008, U.S. Provisional Application No. 61/033,298, filed Mar. 3, 2008, U.S. Provisional Application No. 61/288,242, filed Jan. 20, 2010, U.S. Provisional Application No. 61/362,607, filed Jul. 8, 2010, and International Application No. PCT/US08/77122, filed Sep. 19, 2008. The entire text of each of the above-referenced disclosures (including any appendices) is specifically incorporated by reference herein.

VI. CHLORALKALI-COUPLED REACTIONS OF GROUP 2 HYDROXIDES AND CO₂ TO FORM GROUP 2 CARBONATES

FIG. 38 depicts a simplified process-flow diagram illustrating general, exemplary embodiments of the apparatuses and methods of the present disclosure. This diagram is offered for illustrative purposes only, and thus it merely depicts specific embodiments of the present invention and is not intended to limit the scope of the claims in any way.

In the embodiment shown in FIG. 38, the chor-alkali cell 100 uses power from three sources, external power (DC1) and recaptured power (DC2 and DC3), to drive a reaction represented by equation a. 2NaCl+2H₂O→2NaOH+Cl₂+H₂.  (a)

The sodium hydroxide, chlorine and hydrogen produced from this reaction are delivered to the spray-tower decarbonator 110, photolytic hydrolysis 120 and step 160, respectively.

Carbon dioxide from flue-gas enters the process at the spray-tower decarbonator 110, potentially after initially exchanging waste-heat with a waste-heat/DC generation system. Sodium hydroxide from the chloralkali cell 100 reacts with carbon dioxide in the spray-tower decarbonator 110 according to the reaction represented by equation b. 2NaOH+CO₂→Na₂CO₃+H₂O  (b)

The water produced from this reaction is indirectly delivered back to chloralkali cell 100.

Chlorine from the chloralkali cell 100 is liquefied photolytically with water in the process at 120. The net reaction can be represented by equation c: Cl₂+2H₂O→2HCl+½O₂  (c)

In some embodiments, this reaction or variants thereof are catalyzed by cobalt containing catalysts. See, for example, U.S. Pat. No. 4,764,286, which is specifically incorporated herein by reference in its entirety.

Group-2 metal silicates (CaSiO₃ and/or MgSiO₃) enter the process at 130. These minerals are reacted with hydrochloric acid from the photolytic hydrolysis 120 to form the corresponding group-2 metal chlorides (CaCl₂ and/or MgCl₂), water and sand. The reaction can be represented by equation d. 2HCl+(Ca/Mg)SiO₃→(Ca/Mg)Cl₂+H₂O+SiO₂  (d)

The water produced from this reaction is indirectly delivered back to chloralkali cell 100.

(Ca/Mg)Cl₂ from the group-2 chlorination 130 is delivered to the limestone generator 140, where it reacts indirectly with sodium carbonate from the spray-tower decarbonator 110. This reaction is mediated by hydrogen bridge 150, which connects two half-cell reactions that can be represented by equations e and f. Na₂CO₃+HCl→NaHCO₃+NaCl  (e) NaHCO₃+(Ca/Mg)Cl₂→(Ca/Mg)CO₃+HCl+NaCl  (f)

Power DC3 from the coupling of equations e and f in the form of DC current is delivered from limestone generator 140 to chloralkali cell 100. The sodium chloride produced by equations e and f is delivered to chloralkali cell 100. In this manner, the reactant required to electrolyze (NaCl) has been regenerated, and, given appropriate conditioning, is prepared to be electrolyzed and absorb another cycle of CO₂, thus forming a chemical loop.

The net reaction capturing the summation of equations a-f is shown here as equation g: CO₂+(Ca/Mg)SiO₃→(Ca/Mg)SiO₃+SiO₂  (g)

Hydrogen from chloralkali cell 100 is further reacted with carbon dioxide in step 160 to generate power (DC2), for example, in some embodiments mixing hydrogen with natural gas and burning this mixture in a turbine designed for natural gas power generation and connected to an electrical generator, or, for example, in other embodiments using water-gas shift and Fischer-Tropsch technology. DC2 is delivered in the form of DC current back to chloralkali cell 100.

Through the process shown in FIG. 38 and described herein, power can be returned directly and/or indirectly from some or even all of the hydrochloric-acid produced, while only group-2 carbonates are generated as end-sequestrant material and some or all of the sodium, chlorine and hydrogen is cycled. In so doing, the process effectively uses a lower-energy sodium-based chlorine-electrolysis pathway for the generation of the hydroxide used to capture the carbon-dioxide from its gaseous state.

As noted above, in certain embodiments, the apparatuses and methods of the present disclosure employ brine electrolysis for production of the sodium hydroxide that is used as the absorbent fluid in the decarbonation process. Brine electrolysis is an electrochemical process primarily used in the production of concentrated sodium hydroxide (caustic soda) and chlorine gas, and is typically described throughout the relevant literature by equation h: 2NaCl+2H₂O+e ⁻→2NaOH+H₂(g)+Cl₂(g)  (h)

Brine electrolysis is typically accomplished by three general types of standard electrolysis cells: diaphragm, mercury, and membrane cells. Each of these types of cells produces the same output products from the same input reactants. They differ from each other primarily in the way the reactants and products are separated from each other.

In one embodiment, a membrane cell may be used due to several factors. First, environmental concerns over mercury have reduced the demand for the mercury cell. Second, the diaphragm cells may produce a relatively weak caustic product which contains significant concentrations of salt and chloride ion and requires considerable subsequent reprocessing/separation to remove the significant salt content from the caustic. Third, improvements in fluorinated polymer technology have increased the life-time and electrical efficiency of membrane cell technology, where lifetimes in excess of five years are routinely guaranteed in the industrial markets. Further, the power-per-ton-of-caustic efficiencies exceeds those of both diaphragm and mercury cells in preferred implementations.

Many preferred embodiments may employ membrane cells in this function.

Membrane cells have several advantages over other brine-electrolysis processes. First, membrane cells neither contain nor produce any environmentally sensitive emissions (e.g., mercury) and are electrically efficient when compared with diaphragm and mercury cells. They also employ a concentrated/dilute/make-up NaCl loop such that they may be well-suited for use as a continuous “salt loop” processing unit. Next, NaOH produced in membrane cells without further evaporation/concentration may be a naturally appropriate level of concentration for use in a decarbonation process (e.g., 30-33% NaOH by weight). Further, hydrogen produced by membrane cells is “clean,” approximately “electronic grade,” and relatively clear of NaCl or other contamination. As such, hydrogen may be compressed and tanked off as electronic-grade H₂ gas, used for power-production on-site such as combustion mix with low-grade coal or for combustion-technology gains. Alternatively, the hydrogen may be used for a boiler fuel for the separation processes, which may occur after decarbonation. Membrane cell technology may also be easily scaled from laboratory to plant-size production by the addition of small incremental units. Additionally, chlorine gas produced by the membrane process is less “wet” than that produced by other standard electrolytic processes. As such, a one-stage compression cycle may be sufficient for production of water-treatment grade chlorine.

These methods and devices can be further modified, optimized and scaled up using the principles and techniques of chemistry, chemical engineering, and/or materials science as applied by a person skilled in the art. Such principles and techniques are taught, for example, in U.S. patent application Ser. No. 12/972,006, filed Dec. 17, 2010, U.S. Patent Application Publications 2006/0185985 and 2009/0127127, U.S. patent application Ser. No. 11/233,509, filed Sep. 22, 2005, U.S. Provisional Patent Application No. 60/718,906, filed Sep. 20, 2005; U.S. Provisional Patent Application No. 60/642,698, filed Jan. 10, 2005; U.S. Provisional Patent Application No. 60/612,355, filed Sep. 23, 2004, U.S. patent application Ser. No. 12/235,482, filed Sep. 22, 2008, U.S. Provisional Application No. 60/973,948, filed Sep. 20, 2007, U.S. Provisional Application No. 61/032,802, filed Feb. 29, 2008, U.S. Provisional Application No. 61/033,298, filed Mar. 3, 2008, and International Application No. PCT/US08/77122, filed Sep. 19, 2008. The entire text of each of the above-referenced disclosures (including any appendices) is specifically incorporated by reference herein without disclaimer.

The above examples were included to demonstrate particular embodiments of the invention. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

VII. COMBINED GROUP I AND GROUP II PROCESSES

In other aspects of the present disclosure, it would be preferable to combine processes in order to achieve better energy and materials optimization. For example, a sodium-chlorine based process may be compound with a Group II silicate based process.

A. Sodium-Chlorine Based Process

In some embodiments, the sodium-chlorine based process having the following total reaction may be used: NaCl+CO₂+H₂O→NaHCO₃+½H₂+½Cl₂

The reaction may be divided into a series of steps as shown in Table I.

TABLE I Steps of a Sodium-Chlorine Based Process ΔG Step Equation kJ/mol ΔH kJ/mol 1 NaCl(aq) + H₂O(l) → 211 n/a NaOH(aq) + ½ H₂(g) + ½ Cl₂(g) 2 NaOH(aq) + ½ CO₂(g) → −28.10 −52.33 ½ Na₂CO₃(aq) + ½ H₂O(l) 3 ½ Na₂CO₃(aq) + ½ CO₂(g) + −7.18 −14.01 ½ H₂O(l) → NaHCO₃(aq) 4 NaHCO₃(aq) → NaHCO₃(s) 0.88 −16.32

Step 1 is a chlor-alkali electrolytic step that produces CO₂ absorbing NaOH. In some embodiments, steps 2 and 3 may occur in a single column absorption process to produce NaHCO₃. In other embodiments, for example, if the Na₂CO₃ and NaHCO₃ are produced in two separate columns then steps 2 and 3 occur in the Na₂CO₃ column and in the NaHCO₃ column, respectively.

Sodium-Chlorine based process are further discussed in U.S. Patent Application Publication 2009/0127127, which is incorporated herein by reference.

B. Group II Silicate Based Process

In some embodiments, a group II silicate based process having the following total reaction may be used: CO₂+CaSiO₃SiO₂+CaCO₃

The reaction may be divided into a series of steps as shown in Table II.

TABLE II Steps of a Group II Silicate Based Process ΔH Step Equation kJ/mol 1 2MgCl₂•6H₂O + Δ → 2MgOHCl + 2HCl(g) + 10H₂O(g) 796.2 2 2HCl(g) + 10H₂O(g) → 2HCl(aq) + 10H₂O(l) −589.2 3 CaSiO₃ + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + SiO₂ −97.16 4 2MgOHCl → Mg(OH)₂ + MgCl₂(aq) −123.6 5 Mg(OH)₂ + CaCl₂ + CO₂(g) → MgCl₂(aq) + −94.05 CaCO₃ + H₂O(l) 6 2MgCl₂(aq) + 12H₂O(l) → 2MgCl₂•6H₂O 20.3

Step 1 involves the thermal decomposition of hydrated Group II salt into a Group II hydroxide, HCl gas and steam. In this example, MgCl₂.6H₂O is the salt, and the decomposition products are MgOHCl, HCl gas and steam. The HCl gas and steam exit the decomposition reactor and flow to another vessel and react with a group II silicates feed in order to form silica SiO₂ and in this example CaCl₂. Steps 2 and 3 represent this process step. In some embodiments, the MgOHCl formed in the decomposition reactor is sent to an absorption column where it separates into water soluble MgCl₂ and insoluble Mg(OH)₂ in step 4. Then in step 5, the Mg(OH)₂ reacts with CO₂ to form carbonate and exchanges positions with a calcium ion present from the CaCl₂ resulting in CaCO₃ precipitate and MgCl₂ thereby providing a regeneration of the hydrated salt MgCl₂.6H₂O, in step 6. FIGS. 18-23 represent process-flow diagrams for different non-limiting embodiments of a group II silicate based process. For example, the embodiment summarized in FIG. 18 comprises the reactions of listed in Table II. This embodiments, any of the other embodiments disclosed herein, or modifications thereof may be combined with a sodium-chlorine based process, including the sodium-chlorine based process discussed above.

C. Chlor-Alkali Processes

In some embodiments, products from an electrolytic chlor-alkali reaction, H₂ and Cl₂, may be reacted together to form HCl, which is an exothermic and spontaneous reaction. In some embodiments, this may be accomplished in an HCl burner. In other embodiments, it may be accomplished using an H₂—Cl₂ fuel cell. There are two modes in which this may be done; firstly in an HCl burner or secondly in a H₂—Cl₂ fuel cell.

TABLE III Thermodynamics of H₂—Cl₂ Reactions ΔG ΔH Equation kJ/mol kJ/mol 1 ½ H₂(g) + ½ Cl₂(g) → HCl(g) −95.33 −92.33 2 ½ H₂(g) + ½ Cl₂(g) + H₂O(l) → HCl(aq) −131.12 −166.77 (actually H₃O⁺ Cl⁻ )

Reaction 1 in Table III is the combustion of H₂ and Cl₂ to form hydrogen chloride gas. Reaction 2 in Table III is dissolution of hydrogen chloride gas in water to form hydrochloric acid.

One challenge with HCl burners is obtaining sufficient heat recovery. H₂—Cl₂ fuel cells on the other hand may attain as efficiencies of 70%. See “Evaluation of concepts for hydrogen—chlorine fuel cells” by Magnus Thomassen, Espen Sandnes, Børre Børresen and Reidar Tunold; Department of Materials Science and Engineering, Norwegian, University of Science and Technology, NO-7491, Trondheim, Norway, which is incorporated by reference herein in its entirety. The generated electrical power can be sent back to the electrochemical cell and reduce the net power load. The remaining energy, 30% in some embodiments, is generated as heat, which may be used as to power a Group II silicate based process.

D. Combined Processes

In some embodiments, the Combined Process comprises a sodium-chlorine based process or unit, one or more Group II silicate based process or units, and a chlor-alkali process or unit. In some embodiments, the Combined process comprises two Group II silicate based process or units. In some embodiments, the chlor-alkali based process or unit comprises a fuel cell and/or an HCl burner that enables energy generation through the combustion of hydrogen and chlorine, which may in turn be harnessed for additional CO₂ capturing processes.

FIG. 39 summarizes an embodiment of the Combined Process. In this embodiment, the Group II based process powered by fuel cell waste heat is different from the one powered by the remainder of the power plant waste heat.

In some embodiments, a two Group II silicate based process or unit is powered by waste heat from the fuel cell and an additional and larger Group II silicate based process or unit powered by waste heat from a power plant. One advantage of the Combined Process is reduces the CO₂ penalty value by simultaneously reducing the electrical power requirements and increasing the additional amount of CO₂ captured without any additional energy penalty.

In some embodiments, the H₂ and Cl₂ emanating from a chlor-alkali electrolytic cell will be sent to a H₂—Cl₂ fuel cell where they will react to form HCl. In some embodiments, the electrical power will be sent back to the chlor-alkali unit to reduce incoming electrical power requirements. In some embodiments, the waste heat will be used in a Group II silicate based process or unit to decompose a hydrated salt, for example, MgCl₂.6H₂O.

In some embodiments, the Group II silicate based process or unit that is powered by the fuel cell has a decomposition chamber is simultaneously powered by heat from the fuel cell and/or from an HCl-mineral silicate reactor of the Group II silicate based process. In some embodiments, the HCl produced in the Fuel Cell is sold to market. In some embodiments, it is reacted with more CaSiO₃ in the HCl-Mineral Silicate reactor to form CaCl₂. In some embodiments, this CaCl₂ is an addition to the CaCl₂ normally produced where external HCl is utilized In some embodiments, the absorption column will consume the CaCl₂ up to the stoichiometric amount needed for the completion the CO₂ capturing reaction. See Table II, reaction 5.

In some embodiments, the net chemical reaction of the Combined Process is: 2CaSiO₃+2NaCl+H₂O+3CO₂→2NaHCO₃+CaCl₂+CaCO₃+2SiO₂

In some embodiments, the second Group II silicate based process or unit will use the waste heat from the remainder of the plant to perform an electrical energy penalty free carbon capture. This second Group II silicate based process or unit will typically be much larger than the fuel-cell powered Group II silicate based process or unit. Examples of Group II silicate based processes provided throughout the instant disclosure.

In some embodiments, the power and CO₂ penalty of a Combined Process may be assessed by performing the following calculations.

-   -   1) Ideal Chlor-Alkali.     -   2) Best Available Chlor-Alkali Technology.     -   3) Chlor-Alkali+H₂—Cl₂ Fuel Cell+SkyCycle-Fuel Cell     -   4) Chlor-Alkali+H₂—Cl₂ Fuel Cell+SkyCycle-Fuel         Cell+SkyCycle-Waste Heat (coal fired power plant)     -   5) Chlor-Alkali+H₂—Cl₂ Fuel Cell+SkyCycle-Fuel         Cell+SkyCycle-Waste Heat (natural gas power plant)

For the sample calculations below, 75,000 tonnes per year of CO₂ captured was used as the input. This can be converted to moles/sec CO₂ captured as follows: 75,000 tonnes/year×10⁶ gm/tonne×(1 mole CO2/44.01 gm)×365 days/yr×24 hr/day×3600 sec/hr=54.04 moles/sec.

Case A: Ideal Chlor-Alkali @ 90° C. And 1 Atm. Pressure.

TABLE IV Reaction Voltage Half Reaction: Cl⁻ → ½ Cl2 + e⁻  1.36 V Half Reaction: H₂O + e⁻ → OH⁻ + ½ H₂ 0.828 V Net Rxn.: NaCl_((aq)) + H₂O_((l)) → NaOH_((aq)) + ½ H_(2(g)) + ½ Cl_(2(g)) 2.188 V

At 90° C. Voltage ˜2.17 V. Faraday's Constant=96,485 C/mol

-   -   a) Calculate Required Power under these conditions:         2.17 Volts*96,485 C/mole*54.04 moles/sec*10⁻⁶ MW/W=11.31 MW     -   b) Calculate CO₂ emission index under these conditions:         (11.31 MW/75,000 tonnes/yr)*(1000 kW/MW*365 days/yr*24         hr/day)=1321 kWH/tonne CO2         1321 kWH/tonne CO2*(0.9072 ton/tonne)=1198 kWH/ton CO₂

Case B: “Best Available Technology” (BAT) Chlor-Alkali Under Standard Operating Conditions.

Using 3^(rd) party I-V (current voltage) data, the required power and CO₂ emission index is calculated for BAT. Table V represents a survey of vendor data in kWH/tonne NaOH. The data is converted to kwH/ton CO₂ in Table VI using the formula MW NaOH÷MW CO₂*0.9072 tons/tonne. The BAT, regarding CO₂ capture is that process point with the lowest CO₂ penalty and hence lowest kwH/ton CO₂. This point corresponds the to the expected process point for the 400 MBarg process at 2.59 Volts. The guaranteed process point is a process point that is guaranteed by the vendor to be attainable. The expected point, a lower value is still expected to be attainable but not guaranteed.

TABLE V In kWH/Tonnes NaOH Voltage Curr Den Std. Process 400 Mbarg Volts Amp/m² guaranteed expected guaranteed expected I 2.59 2000 1,779 1,745 1,770 1,738 II 2.704 3000 1,858 1,823 1,848 1,815 III 2.819 4000 1,937 1,900 1,927 1,892 IV 2.934 5000 2,016 1,977 2,006 1,969 V 3.049 6000 2,095 2,055 2,084 2,046

TABLE VI I-V Data in kWH/ton CO₂ 400 Mbarg Proces Std. Process 400 400 Std. Std. MBarg Mbarg Voltage Curr Den Process Process Process Process Voltage Amp/m² guaranteed expected guaranteed expected I 2.59 2000 1,467 1,439 1,460 1,433 II 2.704 3000 1,532 1,503 1,524 1,497 III 2.819 4000 1,597 1,567 1,589 1,560 IV 2.934 5000 1,663 1,631 1,654 1,624 V 3.049 6000 1,728 1,695 1,719 1,688

BAT 400 MBarg Process at 2 kA/m²

-   -   a) Required Power under these conditions may be calculated as         follows:         2.59 Volts*96,485 C/mole*54.04 moles/sec*10⁻⁶ MW/W=13.5 MW     -   b) CO₂ penalty under these conditions may be calculated as         follows:         (13.5 MW/75,000 tonnes/yr)*(1000 kW/MW*365 days/yr*24         hr/day)*(0.9072 ton/tonne)=1433 kWH/ton or 1579 kWH/tonne

In this embodiment, the difference between the CO₂ penalty for the BAT technology and Ideal case is 1433−1198=235 kWH/ton.

Case C: Chlor-Alkali+H₂—Cl₂ Fuel Cell @70% Efficiency+Group II Silicate Based Process with Fuel Cell.

In some embodiments, it is preferable to react the resulting H₂ and Cl₂ in a fuel cell to form hydrochloric acid. The electrical power generated may then be used to subtract from the power consumed to run a chlor-alkali cell. Various tests of fuel cells have yielded efficiencies as high as 70%, as discussed above. The remainder energy will typically exit as waste heat. This waste heat in turn, serves to power another SkyCycle unit.

For a fuel cell, the power generated is based on the reversible available Gibbs Free energy. For HCl data is readily available from sources such as Perry's Handbook for Chemical Engineers, which is incorporated herein by reference. The ΔG_(formation) of aqueous hydrochloric acid from its constituents H₂ gas and Cl₂ gas is −131 kJ/mole.

TABLE VII Info for H₂—Cl₂ fuel cell Half Reaction Voltage ½ Cl₂ + e⁻ → Cl⁻ 1.36 ½ H₂ → H + e⁻ 0 Total ½Cl₂ + ½H₂ → HCl 1.36

This can also be verified using Faraday's Equation, ΔG=−nFE_(o), where n=1 (one electron transfer), F=Faraday's constant=96,485 C/mole, which equals −96485 C/mole*1.36V*0.001 kJ/J or −131.2 kJ/mole. This quantity agrees with the ΔG_(form) for HCl (aqueous) from Perry's.

In some embodiments, the following reactions may be combined as follows: NaCl(aq)+CO_(2(g))+H₂O(l)→NaHCO_(3(aq))½H₂+½Cl₂ ½H₂+½Cl₂→HCl(aq) NaCl+CO₂+H₂O→NaHCO₃+HCl(aq)

In this embodiment, the stoichiometric ratio of CO₂ to HCl is 1:1. Hence HCl generation is 54.04 moles/sec as is the CO₂ generation

-   -   1) Electrical Power generated from Fuel Cell (continued) may be         calculated as follows:         -   A) Given 70% efficiency, power generated (has negative value             since it is generated)         -   B) −(70%*1.36V*96,485 C/mole*54.04 moles/sec*10⁻⁶             MW/W)=−4.96 MW     -   2) Total Electrical Power required may be calculated as follows:         -   A) Total power required=(Power Required for Chlor-Alkali             Cell)−         -   B) For Ideal Chlor-Alkali Cell 11.31 MW−4.96 MW=6.35 MW             -   For BAT Chlor-Alkali Cell: 13.5 MW−4.96 MW=8.54 MW     -   3) Fuel Cell Waste Heat may be calculated as follows:         -   A) Lost efficiency=(1-70%)=30%         -   B) Use AH not AG             ½H_(2(g))+½Cl_(2(g))→HCl_((aq))             ΔH=−166.8 kJ/mole=30%*(54.04 mole/sec)*(−166.8             kJ/mole)=−2.70 MW (heat generated)     -   4) Other Waste Heats may be calculated as follows:         -   A) Heat from Fuel Cell effluent (aqueous HCl) and         -   B) Group II silicate based process (e.g.,             HCl+CaSiO₃(Wollastonite)             CaSiO₃+2HCl(aq)→CaCl₂(aq)+SiO₂+H₂O(l)

TABLE VIII Information for HCl—CaSiO₃ Compound ΔH kJ/mole CaSiO₃ −1581.5 HCl(aq) −166.78 CaCl₂(aq) −875.3 SiO₂ −851.02 H₂O(l) −285.0 ΔH = (−875.3) + (−851.02) + (−285) − [(2 *(−166.78)) − 1581] kJ/mole = −97.16 kJ/mole

-   -   Stoichiometric ratio CaSiO₃:HCl is 1:2     -   Therefor consumption of is 0.5*54.04 moles/sec=27.02 moles/sec         27.02 moles/sec*(−97.16 kJ/mole)*0.001 MW/kW=−2.63 MW (heat         generated)     -   5) Both waste heats may be calculated as follows:         2.63+2.70 MW=5.33 MW     -   6) The additional decomposition from the previously calculated         Fuel Cell waste heats may be calculated in an iterative manner         until it converges.     -   7) Some enthalpies of decomposition reactions are provided here:

TABLE IX Thermodynamic Data for MgCl₂•6H₂O decomposition reaction Compound ΔH kJ/mole MgCl₂•6H₂O −2499.1 HCl_((g)) −92.33 H₂O_((g)) −241.88 MgOHCl −799.6 MgO −601.97

Note that in this embodiment, HCl formed here is HCl gas, whereas the HCl formed in the fuel cell is an aqueous solution, these have very different enthalpies and Gibbs free energies of formation.

In some embodiments, the reactions can occur in two modes: MgCl₂.6H₂O+Δ→MgOHCl+HCl(g)+5H₂O(g)//˜230° C.  Reaction #1 ΔH_(r×n)=(−799.6)+(−92.33)+5*(−241.88)−(−2499.1)=398 kJ/mole MgCl₂.6H₂O+Δ→MgO+2HCl_((g))+5H₂O_((g))//>450° C.  Example #2 ΔH_(r×n)(−601.97)+2*(−92.33)+5*(−241.88)−(−2499.1)=503.4 kJ/mole

In some embodiments, the reaction #1 will be used.

Although the ΔH_(r×n) 398 kJ/mole, two moles of MgOHCl are required per molecule of CO₂ absorbed for some of the reactions specified earlier: 2MgOHCl→Mg(OH)₂+MgCl_(2(aq)) Mg(OH)₂+CO_(2(g))+CaCl_(2(aq))→CaCO₃+MgCl₂+H₂O_((l))

Therefore the ΔH_(r×n) per mole of CO₂ absorbed is 2*398 kJ/mole=796.2 kJ/mole

Also for the reaction: CaSiO₃+2HCl(aq)→CaCl₂(aq)+SiO₂+H₂O(1)

-   -   ΔH_(r×n)-97.16 kJ/mole (see 4 A)     -   8) Theoretical production of extra CO₂ sorbent (MgOHCl) may be         calculated as follows:         -   From #5, added heats are 5.33 MW (generated)         -   A) Additional CO₂ absorbed by extra MgOHCl:             (5.33 MW/796.2 kJ/mole)*1000 kW/MW=6.70 moles/sec CO₂             absorbed         -   B) The HCl from additional decomposition, which reacts with             CaSiO₃ Balancing the decomposition of MgCl₂.6H₂O             2MgCl₂.6H₂O+Δ→2MgOHCl+2HCl(g)+10H₂O(g)  i)             2Mg(OH)Cl→Mg(OH)₂+MgCl2_((aq))  ii)             Mg(OH)₂+CO_(2(g))+CaCl_(2(aq))→CaCO₃+MgCl₂+H₂O_((l))  iii)             CaSiO₃+2HCl(aq)→CaCl₂(aq)+SiO₂+H₂O_((l))  iv)         -   Therefore the ratio of extra CO₂ absorbed (reaction iii), to             extra CaSiO₃ reacted with HCl (reaction iv) generated from             the decomposition of MgCl₂.6H₂O (reaction i) is 1:1.         -   Extra heat, newly generated from the HCl+CaSiO₃ reaction.         -   From Section 4A this ΔH=−97.16 kJ/mole (generated)         -   Therefore, 6.70 moles/sec*97.16 kJ/mole*0.001 MW/kW=0.65 MW         -   C) Total Power from heat generated:             5.33MW+0.65 MW=5.98 MW         -   D) Repeating step 8 B.             -   Sending this heat back to decomposition.                 (5.98 MW/796.2 kJ/mole)*1000 kW/MW=7.51 moles/sec             -   Generating additional heat from the HCl-Wollastonite                 reaction                 7.51 moles/sec*97.16 kJ/mole*0.001 MW/kW=0.73MW             -   And adding this heat to the previous heat.                 0.73 MW+5.33 MW=6.06 MW             -   Repeating these three steps again.                 (6.06 MW/796.2 kJ/mole)*1000 kW/MW=7.61 moles/sec                 7.61 moles/sec*97.16 kJ/mole*0.001 MW/kW=0.74MW                 0.74+5.33 MW=6.07 MW                 (6.07MW/796.2 kJ/mole)*1000 kW/MW=7.63 moles/sec             -   Value finally converges ˜0.74 MW                 7.63 moles/sec*97.16 kJ/mole*0.001 MW/kW=0.74MW             -   Amount of additional CO₂ absorbed ˜7.63 moles/sec     -   9) CO₂ emission penalty for SkyMine+Fuel Cell+SkyCycle-Fuel Cell         may be calculated as follows:         -   A) Extra CO₂ absorbed in tonnes/year may be calculated as             follows:             -   From 8 D, extra CO₂ absorbed=7.63 moles/sec                 44.01 gm/mole CO₂*7.63 moles/sec*3600 sec/hr*24                 hr/day*365 days/year*10⁻⁶ tonne/gm=10,582 tonnes/year         -   B) Total CO₂ absorbed may be calculated as follows:             -   From the beginning of Section III, the original amount                 of CO₂ captured was 75,000 tonnes/year.         -   C) Adding this to the extra CO₂ absorbed.             Total=75,000+10,582 tonnes/year=85,582 tonnes/year         -   D) Final Calculation for CO₂ emission penalty.             -   i) Ideal Chlor-Alkali Cell                 -   Given the net power requirement for Chlor-alkali and                     H₂/Cl₂ Fuel Cell at 70% (section 2B) is 6.35 MW and                     a capture rate of 85,582 tonnes/year.                     6.35 MW/85,582 tonnes/yr.*(1000 kW/MW*365 days/yr*24                     hr/day)*(0.9072 tons/tonne)                 -   589 kWH/ton                 -   or 650 kWH/tonne                 -   The percentage of CO₂ captured by SkyMine is                     75,000/85,582=87.6%                 -   And the percentage of CO₂ captured by the fuel cell                     waste heat SkyCycle is                     10,582/85,582=12.4%             -   ii) BAT Chlor-Alkali Cell                 8.54 MW/85,582 tonnes/yr.*(1000 kW/MW*365 days/yr*24                 hr/day)*(0.9072 tons/tonne)=793 kWH/ton             -   or 874 kWH/tonne

In some embodiments, the percentage CO₂ captured by a sodium-chlorine based process and a Group II silicate based process are the same as for the ideal Chlor-Alkali Cell.

Case 4: Chlor-Alkali+H2-Cl2 Fuel Cell @70% Efficiency+SkyCycle-Fuel Cell+SkyCycle-Remainder of Plant Waster Heat.

In this embodiment (Case 4) the remainder of the plant's waste heat is used, whether coal-fired or natural gas-fired power plant to power an additional Group II silicate based process unit. Using, for examples, the embodiments summarized in FIGS. 18-23, the tabulated value of carbon dioxide capture for each process, percent concentration of carbon dioxide and type of power plant, is listed below. For a plot see FIG. 29.

TABLE X Percent CO2 capture versus % CO2 in the flue gas, mineral silicate composition, decomposition mode, stack gas temperature and type. CaSiO₃—MgOHCl CaSiO₃—MgOHCl CaSiO₃—MgOHCl CaSiO₃—MgOHCl FG at FG at FG at FG at 320° C. 360° C. 400° C. 440° C. % CO₂ COAL COAL COAL COAL  7% 33% 45% 57% 70% 10% 24% 32% 41% 50% 14% 17% 23% 29% 36% 18% 13% 18% 23% 28% CaSiO₃—MgOHCl CaSiO₃—MgO CaSiO₃—MgOHCl CaSiO₃—MgO FG at FG at FG at FG at 550° C. 550° C. 600° C. 600° C. % CO₂ COAL COAL NGAS NGAS  7% 105%  83% 121%  96% 10% 75% 60% 87% 69% 14% 54% 43% 62% 50% 18% 42% 33% 48% 39%

The process used for these comparisons is the CaSiO₃—MgOHCl using the reactions as listed in Table II.

From the Aspen generated plots, the waste heat from the Group II silicate based process from the stack gas of a natural gas power plant captures 87% of the CO₂ emissions (see CaSiO₃—MgOHCl FG at 600° C. NGAS and 10% CO₂. By contrast, the stack gas of a coal fired power plant captures 41% of the CO₂ emissions (see CaSiO₃—MgOHCl FG at 400° C. Coal and 10% CO₂).

Therefore, in some embodiments, a sodium-chlorine based process may be used to trap the remaining 13% (100%−87%) and 59% (100%−41%) of the remaining CO₂ for the two cases respectively.

From section 9D of Case III, the CO₂ emissions for the theoretical chlor-alkali cell+H₂/Cl₂ Fuel Cell at 70% efficiency+Fuel Cell Group II Silicate Based Process case was 589 kwH/ton.

From part D of Case 3, the percent captured by a Sodium-Chlorine Based Process is 87.16% and the percent captured by a Group II Silicate Based Process is 12.4%.

-   -   A) For Coal derived waste heat at 400° C. Coal and 10% CO₂:         -   The CO₂ emission penalty is:             100%−41%=59%             59%*589 kwH/ton=347 kwH/ton or 382 kwH/tonne         -   Percentage of CO₂ capture due to the Sodium-Chlorine Based             Process:             87.6%*59%=51.7%         -   Percentage due to the Group II Silicate Based Process:             (12.4%*59%)+41%=48.3%     -   B) For Natural Gas derived waste heat at 600° C. Coal and 10%         CO₂:         -   The CO₂ emission penalty is:             100%−87%=13%             13%*589 kwH/ton=76 kwH/ton or 84 kwH/tonne         -   Percentage CO₂ capture due to the Sodium-Chlorine Based             Process:             87.6%*13%=11.4%         -   Percentage due to the Group II Silicate Based Process             (12.4%*13%)+87%=88.6%

TABLE XI Percentage of CO₂ capture mode, i.e. SkyMine or SkyCycle for each case. CO₂ penalty Technology Configuration Case kWh/ton SkyMine SkyCycle Ideal Chlor-Alkali 1 1198  100%   0% BAT Chlor-Alkali 2 1433  100%   0% Ideal Chlor-Alkali + H₂—Cl₂ FC 70% eff. + FC 3 589 87.6% 12.4% Group II Silicate Based Process Ideal Chlor-Alkali + H₂—Cl₂ FC 70% eff. + FC 4 347 51.7% 48.3% Group II Silicate Based Process + WH Group II ex. 1 Silicate Based Process Coal Ideal Chlor-Alkali + H₂—Cl₂ FC 70% eff. + FC 4 ex. 76 11.4% 88.6% Group II Silicate Based Process + WH Group II 2 Silicate Based Process NG

VIII. SILICATE MINERALS FOR THE SEQUESTRATION OF CARBON DIOXIDE

In aspects of the present invention there are provided methods of sequestering carbon dioxide using silicate minerals. The silicate minerals make up one of the largest and most important classes of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group. Silicate minerals all contain silicon and oxygen. In some aspects of the present invention, Group 2 silicates may be used to accomplish the energy efficient sequestration of carbon dioxide.

In some embodiments, compositions comprising Group 2 inosilicates may be used. Inosilicates, or chain silicates, have interlocking chains of silicate tetrahedra with either SiO₃, 1:3 ratio, for single chains or Si₄O₁₁, 4:11 ratio, for double chains.

In some embodiments, the methods disclosed herein use compositions comprising Group 2 inosilicates from the pyroxene group. For example, enstatite (MgSiO₃) may be used.

In some embodiments, compositions comprising Group 2 inosilicates from the pyroxenoid group are used. For example, wollastonite (CaSiO₃) may be used. In some embodiments, compositions comprising mixtures of Group 2 inosilicates may be employed, for example, mixtures of enstatite and wollastonite. In some embodiments, compositions comprising mixed-metal Group 2 inosilicates may be used, for example, diopside (CaMgSi₂O₆).

Wollastonite usually occurs as a common constituent of a thermally metamorphosed impure limestone. Typically wollastonite results from the following reaction (equation 26) between calcite and silica with the loss of carbon dioxide: CaCO₃+SiO₂→CaSiO₃+CO₂  (26) In some embodiments, the present invention has the result of effectively reversing this natural process. Wollastonite may also be produced in a diffusion reaction in skarn. It develops when limestone within a sandstone is metamorphosed by a dyke, which results in the formation of wollastonite in the sandstone as a result of outward migration of calcium ions.

In some embodiments, the purity of the Group 2 inosilicate compositions may vary. For example, it is contemplated that the Group 2 inosilicate compositions used in the disclosed processes may contain varying amounts of other compounds or minerals, including non-Group 2 metal ions. For example, wollastonite may itself contain small amounts of iron, magnesium, and manganese substituting for calcium.

In some embodiments, compositions comprising olivine and/or serpentine may be used. CO₂ mineral sequestration processes utilizing these minerals have been attempted. The techniques of Goldberg et al. (2001) are incorporated herein by reference.

The mineral olivine is a magnesium iron silicate with the formula (Mg,Fe)₂SiO₄. When in gem-quality, it is called peridot. Olivine occurs in both mafic and ultramafic igneous rocks and as a primary mineral in certain metamorphic rocks. Mg-rich olivine is known to crystallize from magma that is rich in magnesium and low in silica. Upon crystallization, the magna forms mafic rocks such as gabbro and basalt. Ultramafic rocks, such as peridotite and dunite, can be residues left after extraction of magmas and typically are more enriched in olivine after extraction of partial melts. Olivine and high pressure structural variants constitute over 50% of the Earth's upper mantle, and olivine is one of the Earth's most common minerals by volume. The metamorphism of impure dolomite or other sedimentary rocks with high magnesium and low silica content also produces Mg-rich olivine, or forsterite.

IX. GENERATION OF GROUP 2 CHLORIDES FROM GROUP 2 SILICATES

Group 2 silicates, e.g., CaSiO₃, MgSiO₃, and/or other silicates disclosed herein, may be reacted with hydrochloric acid, either as a gas or in the form of aqueous hydrochloric acid, to form the corresponding Group 2 metal chlorides (CaCl₂ and/or MgCl₂), water and sand. In some embodiments the HCl produced in equation 1 is used to regenerate the MgCl₂ and/or CaCl₂ in equation 3. A process loop is thereby created. Table 1 below depicts some of the common calcium/magnesium containing silicate minerals that may be used, either alone or in combination. Initial tests by reacting olivine and serpentine with HCl have been successful. SiO₂ was observed to precipitate out and MgCl₂ and CaCl₂ were collected.

TABLE 1 Calcium/Magnesium Minerals. Ratio Ratio Group Group 2: Mineral Formula (std. notation) Formula (oxide notation) 2:SiO₂ total Olivine (Mg,Fe)₂[SiO₄] (MgO,FeO)₂•SiO₂ 1:1 1:2 Serpentine Mg₆[OH]₈[Si₄O₁₀] 6MgO•4SiO₂•4H₂O 3:2 undefined Sepiolite Mg₄[(OH)₂Si₆O₁₅]6H₂O 3MgO•Mg(OH)₂•6SiO₂•6H₂O 2:3 undefined Enstatite Mg₂[Si₂O₆] 2MgO•2SiO₂ 1:1 undefined Diopside CaMg[Si₂O₆] CaO•MgO•2SiO₂ 1:1 undefined Tremolite Ca₂Mg₅{[OH]Si₄O₁₁}₂ 2CaO•5MgO•8SiO₂H₂O 7:8 undefined Wollastonite CaSiO₃ CaO•SiO₂ 1:1 undefined See “Handbook of Rocks, Minerals & Gemstones by Walter Schumann Published 1993, Houghton Mifflin Co., Boston, New York, which is incorporated herein by reference.

X. FURTHER EMBODIMENTS

In some embodiments, the conversion of carbon dioxide to mineral carbonates may be defined by two salts. The first salt is one that may be heated to decomposition until it becomes converted to a base (hydroxide and/or oxide) and emits an acid, for example, as a gas. This same base reacts with carbon dioxide to form a carbonate, bicarbonate or basic carbonate salt.

For example, in some embodiments, the present disclosure provides processes that react one or more salts from Tables A-C below with water to form a hydroxides, oxides, and/or a mixed hydroxide halides. Such reactions are typically referred to as decompositions. In some embodiments, the water may be in the form of liquid, steam, and/or from a hydrate of the selected salt. The steam may come from a heat exchanger whereby heat from an immensely combustible reaction, i.e. natural gas and oxygen or hydrogen and chlorine heats a stream of water. In some embodiments, steam may also be generated through the use of plant or factory waste heat. In some embodiments, the halide salt, anhydrous or hydrated, is also heated.

TABLE A Decomposition Salts Li⁺ Na⁺ K⁺ Rb⁺ Cs⁺ F⁻ NC N 4747 N NC N 10906 N 7490 N Cl⁻ 3876 N 19497 N 8295 N 13616 N 7785 N Br⁻ 3006 N 4336 N 9428 N 13814 N 8196 N I⁻ 6110 N 6044 N 11859 N 9806 N 8196 N

TABLE B Decomposition Salts (cont.) Mg⁺² Ca⁺² Sr⁺² Ba⁺² F⁻ 4698 N 3433 N 10346 N 6143 N Cl⁻  4500* 6W* 5847 2W 9855 6W 8098 2W Br⁻ 5010 6W 2743 N 10346 6W 8114 2W I⁻ 2020 N 4960 N 9855 6W 10890 2W *Subsequent tests have proven the heat of reaction within 1.5-4% of the thermodynamically derived value using TGA (thermogravinometric analysis) of heated samples and temperature ramp settings.

TABLE C Decomposition Salts (cont.) Mn⁺² Fe⁺² Co⁺² Ni⁺² Zn⁺² F⁻ 3318 N 2101 N 5847 N 5847 N 3285 N Cl⁻ 5043 6W 3860 4W 3860 6W 4550 6W 8098 4W Br⁻ 5256 6W 11925 4W 9855 6W 5010 6W 4418 4W I⁻ 5043 6W 3055 4W 4123 6W 5831 6W 4271 4W SO₄ ⁻² NC 4W 13485 4W 3351 4W 8985 6W 8344 7W

TABLE D Decomposition Salts (cont.) Ag⁺ La⁺³ F⁻ 2168 N 13255 7W Cl⁻ 5486 N 7490 7W Br⁻ 6242 N 5029 7W I⁻ 6110 N 4813 7W SO₄ ⁻² 6159 N 10561 6W For Tables A-D, the numerical data corresponds to the energy per amount of CO₂ captured in kWh/tonne, NC=did not converge, and NA=data not available.

This same carbonate, bicarbonate or basic carbonate of the first salt reacts with a second salt to do a carbonate/bicarbonate exchange, such that the anion of second salt combines with the cation of the first salt and the cation of the second salt combines with the carbonate/bicarbonate ion of the first salt, which forms the final carbonate/bicarbonate.

In some cases the hydroxide derived from the first salt is reacted with carbon dioxide and the second salt directly to form a carbonate/bicarbonate derived from (combined with the cation of) the second salt. In other cases the carbonate/bicarbonate/basic carbonate derived from (combined with the cation of) the first salt is removed from the reactor chamber and placed in a second chamber to react with the second salt. FIG. 27 shows an embodiment of this 2-salt process.

This reaction may be beneficial when making a carbonate/bicarbonate when a salt of the second metal is desired, and this second metal is not as capable of decomposing to form a CO₂ absorbing hydroxide, and if the carbonate/bicarbonate compound of the second salt is insoluble, i.e. it precipitates from solution. Below is a non-exhaustive list of examples of such reactions that may be used either alone or in combination, including in combination with one or more either reactions discussed herein.

Examples for a Decomposition of a Salt-1 2NaI+H₂O→Na₂O+2HI and/or Na₂O+H₂O→2NaOH MgCl₂.6H₂O→MgO+5H₂O+2HCl and/or MgO+H₂O→Mg(OH)₂ Examples of a Decarbonation 2NaOH+CO₂→Na₂CO₃+H₂O and/or Na₂CO₃+CO₂+H₂O→2NaHCO₃ Mg(OH)₂+CO₂→MgCO₃+H₂O and/or Mg(OH)₂+2CO₂→Mg(HCO₃)₂ Examples of a Carbonate exchange with a Salt-2 Na₂CO₃+CaCl₂→CaCO₃↓+2NaCl Na₂CO₃+2AgNO₃→Ag₂CO₃↓+2NaNO₃ Ca(OH)₂+Na₂CO₃→CaCO₃↓+2NaOH* * In this instance the carbonate, Na₂CO₃ is Salt-2, and the salt decomposed to form Ca(OH)₂, i.e. CaCl₂ is the Salt-1. This is the reverse of some of the previous examples in that the carbonate ion remains with Salt-1.

Known carbonate compounds include H₂CO₃, Li₂CO₃, Na₂CO₃, K₂CO₃, Rb₂CO₃, Cs₂CO₃, BeCO₃, MgCO₃, CaCO₃, MgCO₃, SrCO₃, BaCO₃, MnCO₃, FeCO₃, CoCO₃, CuCO₃, ZnCO₃, Ag₂CO₃, CdCO₃, Al₂(CO₃)₃, Tl₂CO₃, PbCO₃, and La₂(CO₃)₃. Group IA elements are known to be stable bicarbonates, e.g., LiHCO₃, NaHCO₃, RbHCO₃, and CsHCO₃. Group IIA and some other elements can also form bicarbonates, but in some cases, they may only be stable in solution. Typically rock-forming elements are H, C, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mg and Fe. Salts of these that can be thermally decomposed into corresponding hydroxides by the least amount of energy per mole of CO₂ absorbing hydroxide may therefore be considered potential Salt-1 candidates.

Based on the energies calculated in Tables A-D, several salts have lower energies than MgCl₂.6H₂O. Table E below, summarizes these salts and the percent penalty reduction through their use relative to MgCl₂.6H₂O.

TABLE E Section Lower Energy Alternative Salts Compound kw-hr/tonne % reduction MgCl₂•6H2O 4500  0% LiCl 3876 16% LiBr 3006 50% NaBr 4336  4% MgI₂ 2020 123%  CaF₂ 3433 31% CaBr₂ 2743 64% MnF₂ 3318 36% FeF₂ 2102 114%  FeCl₂•4H₂O 3860 17% FeI₂•4H₂O 3055 47% CoCl₂•6H₂O 3860 17% CoI₂•6H₂O 4123  9% CoSO₄•4H₂O 3351 34% ZnF₂•2H₂O 3285 37% ZnBr₂•4H₂O 4418  2% ZnI₂•4H₂O 4271  5% CdF₂ 3137 43% AgF 2168 108% 

The following salts specify a decomposition reaction through their respective available MSDS information.

TABLE F Compound Decomposition Energy Notes MgCl₂•6H₂O 4500 MnCl₂•4H₂O 5043 only Mn⁺² forms a stable carbonate NaI•2H₂O 1023 too rare CoI₂•6H₂O 4123 too rare FeCl₂•4H₂O 3860 May oxidize to ferric oxide, this will not form a stable carbonate LiBr 3006 too rare Mg(NO₃)₂•4H₂O 1606 leaves Nox CoSO₄•4H₂O 3351 somewhat rare leaves SO₃ CdCl₂•2.5H₂O not aval. toxic byproducts Ca(NO₃)₂•4H₂O 2331 leaves NO₂ Compound References MgCl₂•6H₂O MnCl₂•4H₂O http://avogadro.chem.iastate.edu/MSDS/MnCl2.htm NaI₂•H₂O http://www.chemicalbook.com/ProductMSDSDetailCB6170714_EN.htm CoI₂•6H₂O http://www.espimetals.com/index.php/msds/527-cobalt-iodide FeCl₂•4H₂O LiBr http://www.chemcas.com/material/cas/archive/7550-35-8_v1.asp Mg(NO₃)₂•4H₂O http://avogadro.chem.iastate.edu/MSDS/MgNO3-6H2O.htm CoSO₄•4H₂O http://www.chemicalbook.com/ProductMSDSDetailCB0323842_EN.htm CdCl₂•2.5H2O http://www.espimetals.com/index.php/msds/460-cadmium-chloride Ca(NO₃)₂•4H2O http://avogadro.chem.iastate.edu/MSDS/Ca%28NO3%292-4H2O.htm

XI. LIMESTONE GENERATION AND USES

In aspects of the present invention there are provided methods of sequestering carbon dioxide in the form of limestone. Limestone is a sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaCO₃). This mineral has many uses, some of which are identified below.

Limestone in powder or pulverized form, as formed in some embodiments of the present invention, may be used as a soil conditioner (agricultural lime) to neutralize acidic soil conditions, thereby, for example, neutralizing the effects of acid rain in ecosystems. Upstream applications include using limestone as a reagent in desulfurizations.

Limestone is an important stone for masonry and architecture. One of its advantages is that it is relatively easy to cut into blocks or more elaborate carving. It is also long-lasting and stands up well to exposure. Limestone is a key ingredient of quicklime, mortar, cement, and concrete.

Calcium carbonate is also used as an additive for paper, plastics, paint, tiles, and other materials as both white pigment and an inexpensive filler. Purified forms of calcium carbonate may be used in toothpaste and added to bread and cereals as a source of calcium. CaCO₃ is also commonly used medicinally as an antacid.

Currently, the majority of calcium carbonate used in industry is extracted by mining or quarrying. By co-generating this mineral as part of carbon dioxide sequestration in some embodiments, this invention provides a non-extractive source of this important product.

XII. MAGNESIUM CARBONATE GENERATION AND USES

In aspects of the present invention there are provided methods of sequestering carbon dioxide in the form of magnesium carbonate. Magnesium carbonate, MgCO₃, is a white solid that occurs in nature as a mineral. The most common magnesium carbonate forms are the anhydrous salt called magnesite (MgCO₃) and the di, tri, and pentahydrates known as barringtonite (MgCO₃.2H₂O), nesquehonite (MgCO₃.3H₂O), and lansfordite (MgCO₃.5H₂O), respectively. Magnesium carbonate has a variety of uses; some of these are briefly discussed below.

Magnesium carbonate may be used to produce magnesium metal and basic refractory bricks. MgCO₃ is also used in flooring, fireproofing, fire extinguishing compositions, cosmetics, dusting powder, and toothpaste. Other applications are as filler material, smoke suppressant in plastics, a reinforcing agent in neoprene rubber, a drying agent, a laxative, and for color retention in foods. In addition, high purity magnesium carbonate is used as antacid and as an additive in table salt to keep it free flowing.

Currently magnesium carbonate is typically obtained by mining the mineral magnesite. By co-generating this mineral as part of carbon dioxide sequestration in some embodiments, this invention provides a non-extractive source of this important product.

XIII. SILICON DIOXIDE GENERATION AND USES

In aspects of the present invention there are provided methods of sequestering carbon dioxide that produce silicon dioxide as a byproduct. Silicon dioxide, also known as silica, is an oxide of silicon with a chemical formula of SiO₂ and is known for its hardness. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms. Silica is the most abundant mineral in the Earth's crust. This compound has many uses; some of these are briefly discussed below.

Silica is used primarily in the production of window glass, drinking glasses and bottled beverages. The majority of optical fibers for telecommunications are also made from silica. It is a primary raw material for many whiteware ceramics such as earthenware, stoneware and porcelain, as well as industrial Portland cement.

Silica is a common additive in the production of foods, where it is used primarily as a flow agent in powdered foods, or to absorb water in hygroscopic applications. In hydrated form, silica is used in toothpaste as a hard abrasive to remove tooth plaque. Silica is the primary component of diatomaceous earth which has many uses ranging from filtration to insect control. It is also the primary component of rice husk ash which is used, for example, in filtration and cement manufacturing.

Thin films of silica grown on silicon wafers via thermal oxidation methods can be quite beneficial in microelectronics, where they act as electric insulators with high chemical stability. In electrical applications, it can protect the silicon, store charge, block current, and even act as a controlled pathway to limit current flow.

Silica is typically manufactured in several forms including glass, crystal, gel, aerogel, fumed silica, and colloidal silica. By co-generating this mineral as part of carbon dioxide sequestration in some embodiments, this invention provides another source of this important product.

XIV. SEPARATION OF PRODUCTS

Separation processes may be employed to separate carbonate and bicarbonate products from the liquid solution and/or reaction mixture. By manipulating the basic concentration, temperature, pressure, reactor size, fluid depth, and degree of carbonation, precipitates of one or more carbonate and/or bicarbonate salts may be caused to occur. Alternatively, carbonate/bicarbonate products may be separated from solution by the exchange of heat energy with incoming flue-gases.

The exit liquid streams, depending upon reactor design, may include water, CaCO₃, MgCO₃, Ca(HCO₃)₂, Mg(HCO₃)₂, Ca(OH)₂, Ca(OH)₂, NaOH, NaHCO₃, Na₂CO₃, and other dissolved gases in various equilibria. Dissolved trace emission components such as H₂SO₄, HNO₃, and Hg may also be found. In one embodiment, removing/separating the water from the carbonate product involves adding heat energy to evaporate water from the mixture, for example, using a reboiler. Alternatively, retaining a partial basic solution and subsequently heating the solution in a separating chamber may be used to cause relatively pure carbonate salts to precipitate into a holding tank and the remaining hydroxide salts to recirculate back to the reactor. In some embodiments, pure carbonate, pure bicarbonate, and mixtures of the two in equilibrium concentrations and/or in a slurry or concentrated form may then be periodically transported to a truck/tank-car. In some embodiments, the liquid streams may be displaced to evaporation tanks/fields where the liquid, such as water, may be carried off by evaporation.

The release of gaseous products includes a concern whether hydroxide or oxide salts will be released safely, i.e., emitting “basic rain.” Emission of such aerosolized caustic salts may be prevented in some embodiments by using a simple and inexpensive condenser/reflux unit.

In some embodiments, the carbonate salt may be precipitated using methods that are used separately or together with a water removal process. Various carbonate salt equilibria have characteristic ranges where, when the temperature is raised, a given carbonate salt, e.g., CaCO₃ will naturally precipitate and collect, which makes it amenable to be withdrawn as a slurry, with some fractional NaOH drawn off in the slurry.

XV. RECOVERY OF WASTE-HEAT

Because certain embodiments of the present invention are employed in the context of large emission of CO₂ in the form of flue-gas or other hot gases from combustion processes, such as those which occur at a power plant, there is ample opportunity to utilize this ‘waste’ heat, for example, for the conversion of Group 2 chlorides salts into Group 2 hydroxides. For instance, a typical incoming flue-gas temperature (after electro-static precipitation treatment, for instance) is approximately 300° C. Heat exchangers can lower that flue-gas to a point less than 300° C., while warming the water and/or Group 2 chloride salt to facilitate this conversion.

Generally, since the flue-gas that is available at power-plant exits at temperatures between 100° C. (scrubbed typical), 300° C. (after precipitation processing), and 900° C. (precipitation entrance), or other such temperatures, considerable waste-heat processing can be extracted by cooling the incoming flue-gas through heat-exchange with a power-recovery cycle, for example an ammonia-water cycle (e.g., a “Kalina” cycle), a steam cycle, or any such cycle that accomplishes the same thermodynamic means. Since some embodiments of the present invention rely upon DC power to accomplish the manufacture of the reagent/absorbent, the process can be directly powered, partially or wholly, by waste-heat recovery that is accomplished without the normal transformer losses associated with converting that DC power to AC power for other uses. Further, through the use of waste-heat-to-work engines, significant efficiencies can be accomplished without an electricity generation step being employed at all. In some conditions, these waste-heat recovery energy quantities may be found to entirely power embodiments of the present invention.

XVI. FURTHER EMBODIMENTS

As noted above, some embodiments of the apparatuses and methods of the present disclosure produce a number of useful intermediates, by-products, and final products from the various reaction steps, including hydrogen chloride, Group 2 carbonate salts, Group 2 hydroxide salts, etc. In some embodiments, some or all of these may be used in one or more of the methods described below. In some embodiments, some or all of one of the starting materials or intermediates employed in one or more of the steps described above are obtained using one or more of the methods outlined below.

A. Hydrogen Energy Recapture Loop

Several techniques may used recapture energy from the hydrogen generated by embodiments of the present invention. For example, the hydrogen may be co-burned with coal to improve coal-fired emissions. Another technique involves employing a hydrogen/oxygen fuel cell for the generation of DC electricity. Yet another technique involves the burning of hydrogen in a turbine connected to an electrical generator. Still another technique involves the mixing of hydrogen with natural gas and burning this mixture in a turbine designed for natural gas power generation and connected to an electrical generator. Any of these techniques may be used alone or in combination, in some cases, together with other techniques not specifically mentioned.

In one embodiment, commercial fuel-cell production of DC electricity may be advantageous due to the easy-to-handle and safe operations at sub-atmospheric pressures. Immediate consumption of the produced hydrogen may also directly reduce the electrical load cost for the brine electrolysis. Further, since the hydrogen-energy recovery cycle may be produced with off-peak electrical production, H₂ may be subsequently used to provide electricity during on-peak loads, the present disclosure provides for making reactants at low-cost while subsequently producing auxiliary high-cost on-peak electricity and simultaneously performing a decarbonation process. The economic utility of an H₂ energy recovery cycle to increase the peak power production of a plant by augmenting the current production with H₂ combustion capacity as either fuel or in a fuel cell may provide for the utility of a self-consumption basis.

B. Use of Chlorine for the Chlorination of Group 2 Silicates

In some embodiments the chlorine gas may be liquefied to hydrochloric acid that is then used to chlorinate Group 2 silicate minerals. Liquefaction of chlorine and subsequent use of the hydrochloric acid is particularly attractive especially in situations where the chlorine market is saturated. Liquefaction of chlorine may be accomplished according to equation 27: Cl₂(g)+2H₂O(l)+hν(363 nm)→2HCl(l)+½O₂(g)  (27) In some embodiments, the oxygen so produced may be returned to the air-inlet of the power plant itself, where it has been demonstrated throughout the course of power-industry investigations that enriched oxygen-inlet plants have (a) higher Carnot-efficiencies, (b) more concentrated CO₂ exit streams, (c) lower heat-exchange to warm inlet air, and (d) other advantages over non-oxygen-enhanced plants. In some embodiments, the oxygen may be utilized in a hydrogen/oxygen fuel cell. In some embodiments, the oxygen may serve as part of the oxidant in a turbine designed for natural gas power generation, for example, using a mixture of hydrogen and natural gas.

C. Use of Chlorine for the Chlorination of Group 2 Hydroxides

In some embodiments the chlorine gas may be reacted with a Group 2 hydroxide salts to yield a mixture of a chloride and a hypochlorite salts (equation 28). For example, HCl may be sold as a product and the Group 2 hydroxide salt may be used to remove excess chlorine. Ca/Mg(OH)₂+Cl₂→½Ca/Mg(OCl)₂+½Ca/MgCl₂+H₂O  (28) The Group 2 hypochlorites may then be decomposed using a cobalt or nickel catalyst to form oxygen and the corresponding chloride (equation 29). Ca/Mg(OCl)₂→Ca/MgCl₂+O₂  (29) The calcium chloride and/or the magnesium chloride may then be recovered.

XVII. REMOVAL OF OTHER POLLUTANTS FROM SOURCE

In addition to removing CO₂ from the source, in some embodiments of the invention, the decarbonation conditions will also remove SO_(X) and NO_(X) and, to a lesser extent, mercury. In some embodiments of the present invention, the incidental scrubbing of NO_(X), SO_(X), and mercury compounds can assume greater economic importance; i.e., by employing embodiments of the present invention, coals that contain large amounts of these compounds can be combusted in the power plant with, in some embodiments, less resulting pollution than with higher-grade coals processed without the benefit of the CO₂ absorption process. Such principles and techniques are taught, for example, in U.S. Pat. No. 7,727,374, U.S. patent application Ser. No. 11/233,509, filed Sep. 22, 2005, U.S. Provisional Patent Application No. 60/718,906, filed Sep. 20, 2005; U.S. Provisional Patent Application No. 60/642,698, filed Jan. 10, 2005; U.S. Provisional Patent Application No. 60/612,355, filed Sep. 23, 2004, U.S. patent application Ser. No. 12/235,482, filed Sep. 22, 2008, U.S. Provisional Application No. 60/973,948, filed Sep. 20, 2007, U.S. Provisional Application No. 61/032,802, filed Feb. 29, 2008, U.S. Provisional Application No. 61/033,298, filed Mar. 3, 2008, U.S. Provisional Application No. 61/288,242, filed Jan. 20, 2010, U.S. Provisional Application No. 61/362,607, filed Jul. 8, 2010, and International Application No. PCT/US08/77122, filed Sep. 19, 2008. The entire text of each of the above-referenced disclosures (including any appendices) is specifically incorporated by reference herein.

XVIII. EXAMPLES

The following examples are included to demonstrate some embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

Example 1 Process Simulation of Capture CO₂ from Flue Gas Using CaCl₂ to Form CaCO₃

One embodiment of the present invention was simulated using Aspen Plus v. 7.1 software using known reaction enthalpies, reaction free energies and defined parameters to determine mass and energy balances and suitable conditions for capturing CO₂ from a flue gas stream utilizing CaCl₂ and heat to form CaCO₃ product. These results show that it is possible to capture CO₂ from flue gas using inexpensive raw materials, CaCl₂ and water, to form CaCO₃.

Part of the defined parameters includes the process flow diagram shown in FIG. 5. Results from the simulation suggest that it is efficient to recirculate an MgCl₂ stream to react with H₂O and heat to form Mg(OH)₂. This Mg(OH)₂ then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂ formed is recycled to the first reactor to begin the process again. This process is not limited to any particular source for CaCl₂. For example, it may be obtained from reacting calcium silicate with HCl to yield CaCl₂.

Constraints and parameters specified for this simulation include:

-   -   The reactions were run at 100% efficiencies with no losses. The         simulations can be modified when pilot runs determine the         reaction efficiencies.     -   Simulations did not account for impurities in the CaCl₂ feed         stock or in any make-up MgCl₂ required due to losses from the         system.

The results of this simulation indicate a preliminary net energy consumption of approximately 130 MM Btu/hr. Tables 2a and 2b provide mass and energy accounting for the various streams (the columns in the table) of the simulated process. Each stream corresponds to the stream of FIG. 5.

The process consists of two primary reaction sections and one solids filtration section. The first reactor heats MgCl₂/water solution causing it to break down into a HCl/H₂O vapor stream and a liquid stream of Mg(OH)₂. The HCl/H₂O vapor stream is sent to the HCl absorber column. The Mg(OH)₂ solution is sent to reactor 2 for further processing. The chemical reaction for this reactor can be represented by the following equation: MgCl₂+2H₂O→Mg(OH)₂+2HCl  (30)

A CaCl₂ solution and a flue gas stream are added to the MgCl₂ in reactor 2. This reaction forms CaCO₃, MgCl₂ and water. The CaCO₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. The chemical reaction for this reactor can be represented by the following equation: Mg(OH)₂+CaCl₂+CO₂→CaCO₃(s)+MgCl₂+H₂O  (31)

The primary feeds to this process are CaCl₂, flue gas (CO₂) and water. MgCl₂ in the system is used, reformed and recycled. The only MgCl₂ make-up required is to replace small amounts that leave the system with the CaCO₃ product, and small amounts that leave with the HCl/water product.

This process is a net energy user. There is cross heat exchange to recover the heat in high temperature streams to preheat the feed streams. Significant heat recovery may be obtained by reacting the concentrated HCl thus formed with silicate minerals.

TABLE 2a Mass and Energy Accounting for Simulation of Capture CO₂ from Flue Gas Using CaCl₂ to form CaCO₃. Process Stream Names 1 2 3 BOTTOMS CaCl₂ CaCO₃ FG-IN H₂O H₂O—MgOH Temperature F. 485.8 151.6 250 95 77 95 104 0 536 Pressure psia 15 15 15 15 15 15 15 15 15 Vapor Frac 0 0 0.025 0 0 1 0 0 Mole Flow 1594.401 7655.248 7653.691 3568.272 139.697 139.502 611.154 2220.337 1594.401 lbmol/hr Mass Flow lb/hr 53195.71 162514.8 162514.8 115530.1 15504 13962.37 19206 40000 53195.71 Volume Flow 38.289 238.669 12389.12 114.43 14.159 30680.73 80.111 40.178 gal/min Enthalpy −214.568 −918.028 −909.155 −574.405 −47.795 −27.903 −273.013 −205.695 MMBtu/hr H₂O 1473.175 105624.1 105603 33281.39 750.535 40000 1473.172 H₂ Cl₂ HCl trace trace 0.001 trace trace CO₂ <0.001 0.091 0.005 6158.236 CO O₂ 0.055 0.055 0.055 2116.894 N₂ 0.137 0.137 0.137 10180.34 CaCl₂ 15504 Ca(OH)₂ CaCO₃ Mg(OH)₂ Mg(OH)Cl MgCl₂ MgCO₃ Ca(O)Cl₂ CaCl₂O₂ Ca²⁺ 7.797 trace 7.797 Mg²⁺ 11114.84 14507.52 14506.86 11942.37 11115.59 H⁺ <0.001 trace trace trace trace <0.001 CaOH⁺ <0.001 trace <0.001 MgOH⁺ 22.961 15.364 17.613 25.319 20.435 HClO MgCO₃—3W MgCl₂(s) MgCl₂—6W 21433.25 MgCl₂—4W CaCl₂(s) CaCO₃(s) 13962.37 13962.37 MgCO₃(s) 0.174 CaCl₂—6W 42.623 CaCl₂—4W CaCl₂—2W MgCl₂—2W MgCl₂—W Ca(OH)₂(s) Mg(OH)₂(s) 8137.518 7.043 5.576 0.08 8139.306 ClO⁻ HCO₃ ⁻ 0.001 <0.001 0.119 Cl⁻ 32447.21 42352.6 42338.81 34877.24 32447.21 OH⁻ <0.001 0.001 0.001 <0.001 <0.001 <0.001 CO₃ ²⁻ trace trace 0.001 H₂O 0.028 0.65 0.65 0.288 0.039 1 0.028 H₂ Cl₂ HCl trace trace  3 PPB trace trace CO₂ trace 563 PPB  40 PPB 0.321 CO O₂ 336 PPB 336 PPB 473 PPB 0.11 N₂ 844 PPB 844 PPB  1 PPM 0.53 CaCl₂ 1 Ca(OH)₂ CaCO₃ Mg(OH)₂ Mg(OH)Cl MgCl₂ MgCO₃ Ca(O)Cl₂ CaCl₂O₂ Ca²⁺ 48 PPM trace 67 PPM Mg²⁺ 0.209 0.089 0.089 0.103 0.209 H⁺  1 PPB trace trace trace trace  5 PPB CAOH⁺  1 PPB trace  1 PPB MgOH⁺ 432 PPM  95 PPM 108 PPM  219 PPM  384 PPM  HClO MgCO₃—3W MgCl₂(s) MgCl₂—6W 0.186 MgCl₂—4W CaCl₂(s) CaCO₃(s) 0.121 1 MgCO₃(s)  1 PPM CaCl₂—6W 262 PPM  CaCl₂—4W CaCl₂—2W MgCl₂—2W MgCl₂—W Ca(OH)₂(s) Mg(OH)₂(s) 0.153 43 PPM 34 PPM 691 PPB 0.153 ClO⁻ HCO₃ ⁻  5 PPB trace  1 PPM Cl⁻ 0.61 0.261 0.261 0.302 0.61 OH⁻ trace  6 PPB  6 PPB trace  2 PPB trace CO₃ ²⁻ trace trace  12 PPB H₂O 81.774 5863.026 5861.857 1847.398 41.661 2220.337 81.773 H₂ Cl₂ HCl trace trace <0.001 trace trace CO₂ trace 0.002 <0.001 139.929 CO O₂ 0.002 0.002 0.002 66.155 N₂ 0.005 0.005 0.005 363.408 CaCl₂ 139.697 Ca(OH)₂ CaCO₃ Mg(OH)₂ Mg(OH)Cl MgCl₂ MgCO₃ Ca(O)Cl₂ CaCl₂O₂ Ca²⁺ 0.195 trace 0.195 Mg²⁺ 457.328 596.922 596.894 491.376 457.358 H⁺ <0.001 trace trace trace trace <0.001 CAOH⁺ trace trace trace MgOH⁺ 0.556 0.372 0.426 0.613 0.495 HClO MgCO₃—3W MgCl₂(s) MgCl₂—6W 105.426 MgCl₂—4W CaCl₂(s) CaCO₃(s) 139.502 139.502 MgCO₃(s) 0.002 CaCl₂—6W 0.195 CaCl₂—4W CaCl₂—2W MgCl₂—2W MgCl₂—W Ca(OH)₂(s) Mg(OH)₂(s) 139.533 0.121 0.096 0.001 139.564 ClO⁻ HCO₃ ⁻ <0.001 trace 0.002 Cl⁻ 915.211 1194.604 1194.215 983.753 915.211 OH⁻ trace <0.001 <0.001 trace trace trace CO₃ ²⁻ trace trace <0.001 H₂O 0.051 0.766 0.766 0.518 0.068 1 0.051 H₂ Cl₂ HCl trace trace  2 PPB trace trace CO₂ trace 271 PPB  29 PPB 0.229 CO O₂ 223 PPB 223 PPB 478 PPB 0.108 N₂ 640 PPB 640 PPB  1 PPM 0.595 CaCl₂ 1 Ca(OH)₂ CaCO₃ Mg(OH)₂ Mg(OH)Cl MgCl₂ MgCO₃ Ca(O)Cl₂ CaCl₂O₂ Ca²⁺ 25 PPM trace 55 PPM Mg²⁺ 0.287 0.078 0.078 0.138 0.287 H⁺  49 PPB trace trace trace  2 PPB 156 PPB CaOH⁺ trace trace trace MgOH⁺ 349 PPM  49 PPM 56 PPM 172 PPM  310 PPM  HClO MgCO₃—3W MgCl₂(s) MgCl₂—6W 0.03 MgCl₂—4W CaCl₂(s) CaCO₃(s) 0.039 1 MgCO₃(s) 269 PPB CaCl₂—6W 25 PPM CaCl₂—4W CaCl₂—2W MgCl₂—2W MgCl₂—W Ca(OH)₂(s) Mg(OH)₂(s) 0.088 16 PPM 12 PPM 383 PPB 0.088 ClO⁻ HCO₃ ⁻  2 PPB trace 547 PPB Cl⁻ 0.574 0.156 0.156 0.276 0.574 OH⁻  1 PPB  8 PPB  7 PPB trace  2 PPB  1 PPB CO₃ ²⁻ trace trace  6 PPB PH 5.319 6.955 5.875 7.557 6.999 5.152

TABLE 2b Mass and Energy Accounting for Simulation of Capture CO₂ from Flue Gas Using CaCl₂ to form CaCO₃. Process Stream Names H₂O—IN HCl—H₂O Mg—CaCl₂ MgOH—O1 RETURN RX3-VENT Temperature F. 77 536 250 286.8 95 95 Pressure 15 15 15 15 15 15 psia Vapor Frac 0 1 0.025 0.021 0 1 Mole Flow 3383.073 5781.846 7655.866 3814.738 3427.371 433.305 lbmol/hr Mass Flow 60947 109319.3 162515 93195.71 101567.8 12375.59 lb/hr Volume 122.063 512251.6 12240.14 5364.891 104.123 21428.56 Flow gal/min Enthalpy −415.984 −561.862 −909.177 −487.581 −502.044 −0.364 MMBtu/hr H₂O 60947 99124.11 105634.7 41473.17 33262.52 59.861 H₂ Cl₂ HCl 10195.18 0.087 0.009 trace trace CO₂ trace 18.689 CO O₂ 0.055 2116.839 N₂ 0.137 10180.2 CaCl₂ Ca(OH)₂ CaCO₃ Mg(OH)₂ Mg(OH)Cl MgCl₂ MgCO₃ Ca(O)Cl₂ CaCl₂O₂ Ca²⁺ 7.797 Mg²⁺ 14519.48 11116.3 11938.09 H⁺ trace <0.001 trace trace CaOH⁺ <0.001 MgOH⁺ 0.112 17.999 25.309 HClO MgCO₃—3W MgCl₂(s) MgCl₂—6W 21468.81 MgCl₂—4W CaCl₂(s) CaCO₃(s) MgCO₃(s) 0.175 CaCl₂—6W CaCl₂—4W CaCl₂—2W MgCl₂—2W MgCl₂—W Ca(OH)₂(s) Mg(OH)₂(s) 8141.025 0.024 ClO⁻ HCO₃ ⁻ trace Cl⁻ 42360.62 32447.2 34864.84 OH⁻ <0.001 trace <0.001 <0.001 CO₃ ²⁻ trace Mass Frac H₂O 1 0.907 0.65 0.445 0.327 0.005 H₂ Cl₂ HCl 0.093 534 PPB 92 PPB trace trace CO₂ trace 0.002 CO O₂ 538 PPB 0.171 N₂  1 PPM 0.823 CaCl₂ Ca(OH)₂ CaCO₃ Mg(OH)₂ Mg(OH)Cl MgCl₂ MgCO₃ Ca(O)Cl₂ CaCl₂O₂ Ca²⁺ 77 PPM Mg²⁺ 0.089 0.119 0.118 H⁺ trace  2 PPB trace trace CaOH⁺  1 PPB MgOH⁺ 689 PPB 193 PPM 249 PPM HClO MgCO₃—3W MgCl₂(s) MgCl₂—6W 0.211 MgCl₂—4W CaCl₂(s) CaCO₃(s) MgCO₃(s)  2 PPM CaCl₂—6W CaCl₂—4W CaCl₂—2W MgCl₂—2W MgCl₂—W Ca(OH)₂(s) Mg(OH)₂(s) 0.087 240 PPB ClO⁻ HCO₃ ⁻ trace Cl⁻ 0.261 0.348 0.343 OH⁻ 2 PPB trace  2 PPB trace CO₃ ²⁻ trace H₂O 3383.073 5502.224 5863.617 2302.111 1846.35 3.323 H₂ Cl₂ HCl 279.622 0.002 <0.001 trace trace CO₂ trace 0.425 CO O₂ 0.002 66.154 N₂ 0.005 363.404 CaCl₂ Ca(OH)₂ CaCO₃ Mg(OH)₂ Mg(OH)Cl MgCl₂ MgCO₃ Ca(O)Cl₂ CaCl₂O₂ Ca²⁺ 0.195 Mg²⁺ 597.414 457.388 491.201 H⁺ trace <0.001 trace trace CaOH⁺ trace MgOH⁺ 0.003 0.436 0.613 HClO MgCO₃—3W MgCl₂(s) MgCl₂—6W 105.601 MgCl₂—4W CaCl₂(s) CaCO₃(s) MgCO₃(s) 0.002 CaCl₂—6W CaCl₂—4W CaCl₂—2W MgCl₂—2W MgCl₂—W Ca(OH)₂(s) Mg(OH)₂(s) 139.593 <0.001 ClO⁻ HCO₃ ⁻ trace Cl⁻ 1194.83 915.211 983.403 OH⁻ trace trace trace trace CO₃ ²⁻ trace H₂O 1 0.952 0.766 0.603 0.539 0.008 H₂ Cl₂ HCl 0.048 311 PPB 62 PPB trace trace CO₂ trace 980 PPM CO O₂ 498 PPB 0.153 N₂  1 PPM 0.839 CaCl₂ Ca(OH)₂ CaCO₃ Mg(OH)₂ Mg(OH)Cl MgCl₂ MgCO₃ Ca(O)Cl₂ CaCl₂O₂ Ca²⁺  57 PPM Mg²⁺ 0.078 0.12 0.143 H⁺ 2 PPB  43 PPB trace trace CaOH⁺ trace MgOH⁺ 354 PPB 114 PPM 179 PPM HClO MgCO₃—3W MgCl₂(s) MgCl₂—6W 0.031 MgCl₂—4W CaCl₂(s) CaCO₃(s) MgCO₃(s) 607 PPB CaCl₂—6W CaCl₂—4W CaCl₂—2W MgCl₂—2W MgCl₂—W Ca(OH)₂(s) Mg(OH)₂(s) 0.037 122 PPB ClO⁻ HCO₃ ⁻ trace Cl⁻ 0.156 0.24 0.287 OH⁻ 2 PPB trace  2 PPB trace CO₃ ²⁻ trace PH 6.999 3.678 5.438 7.557

Example 2 (Case 1)—Process Simulation of Magnesium Ion Catalyzed Capture CO₂ from Flue Gas Using CaCl₂ to Form CaCO₃

Results from the simulation suggest that it is efficient to heat a MgCl₂.6H₂O stream in three separate dehydration reactions, each in its own chamber, followed by a decomposition reaction, also in its own chamber, to form Mg(OH)Cl and HCl, i.e. total of four chambers. The Mg(OH)Cl is reacted with H₂O to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂.6H₂O formed is recycled along with the earlier product to the first reactor to begin the process again.

This process is not limited to any particular source for CaCl₂. For example, it may be obtained from reacting calcium silicate with HCl to yield CaCl₂.

Constraints and parameters specified for this simulation include:

-   -   The reactions were run at 100% efficiencies with no losses. The         simulations can be modified when pilot runs determine the         reaction efficiencies.     -   Simulations did not account for impurities in the CaCl₂ feed         stock or in any make-up MgCl₂ required due to losses from the         system.     -   Part of the defined parameters include the process flow diagram         shown in FIG. 6.

The results of this simulation indicate a preliminary net energy consumption of 5946 kwh/tonne CO₂. Table 3 provides mass and energy accounting for the various streams of the simulated process. Each stream corresponds to the stream of FIG. 6.

The process consists of two primary reactors and one solids filtration section. The first reactor heats MgCl₂.6H₂O causing it to break down into a HCl/H₂O vapor stream and a solid stream of Mg(OH)Cl. The HCl/H₂O vapor stream is sent to a heat exchanger to recover extra heat. The Mg(OH)₂ formed from the Mg(OH)Cl is sent to reactor 2 for further processing. Chemical reaction(s) occurring in this reactor include the following: MgCl₂.6H₂O+Δ→Mg(OH)Cl+5H₂O↑+HCl↑  (32) 2Mg(OH)Cl(aq)→Mg(OH)₂+MgCl₂  (33)

A CaCl₂ solution and a flue gas stream are added to the Mg(OH)₂ in reactor 2. This reaction forms CaCO₃, MgCl₂ and water. The CaCO₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. Chemical reaction(s) occurring in this reactor include the following: Mg(OH)₂+CaCl₂+CO₂→CaCO₃↓(s)+MgCl₂+H₂O  (34)

The primary feeds to this process are CaCl₂, flue gas (CO₂) and water. MgCl₂ in the system is used, reformed and recycled. The only MgCl₂ make-up required is to replace small amounts that leave the system with the CaCO₃ product, and small amounts that leave with the HCl/water product.

This process is a net energy user. The amount of energy is under investigation and optimization. There is cross heat exchange to recover the heat in high temperature streams to preheat the feed streams.

The steps for this process (Case 1) are summarized below:

CASE 1 3 STEP Dehydration then Decomposition Hexahydrate is dehydrated in 3 separate chambers. Step 1 hex to tetra, Step 2 tetra to di, Step 3 di to mono. Monohydrate is decomposed into 80% Mg(OH)Cl 20% MgCl₂ in a fourth chamber. CO₂ Absorbed 53333 MTPY CaCl₂ 134574 MTPY HCl Dry 88368 MTPY CaCO₃ 105989 MTPY Hexahydrate recycled 597447 MTPY HEX TO TETRA (100° C.) 1757 kWh/tonne CO₂ TETRA TO DI (125 C. °) 2135 kWh/tonne CO₂ DI TO MONO (160° C. & HCl PP) 1150 kWh/tonne CO₂ DECOMPOSITION (130° C.) 1051 kWh/tonne CO₂ TO 80% Mg(OH)Cl 20% MgCl₂ YIELDS 90% HCl VAPOR 0.9 MW Heat Recovery 148 kWh/tonne CO₂ from 28% HCl vapor TOTAL 5946 kWh/tonne CO₂

TABLE 3a Mass and Energy Accounting for Case 1 Simulation. Process Stream Names CaCl₂ CaCO₃ FLUEGAS H₂O H₂O-1 H₂O-2 HCl-PP HCl VAPOR Temperature C. 25 95 104 25 100 125 160 130 Pressure psia 14.7 14.7 15.78 14.7 16.166 16.166 16.166 14.696 Mass VFrac 0 0 1 0 1 1 1 1 Mass SFrac 1 1 0 0 0 0 0 0 Mass Flow tonne/year 134573.943 121369.558 166332.6 290318.99 105883.496 105890.399 17179.526 97647.172 Volume Flow gal/min 30.929 22.514 76673.298 8099.644 82228.086 87740.919 10242.935 48861.42 Enthalpy MW −30.599 −46.174 −17.479 −146.075 −44.628 −44.47 −3.258 −10.757 Density lb/cuft 136.522 169.146 0.068 1.125 0.04 0.038 0.053 0.063 H₂O 0 0 6499.971 290318.99 105883.496 105885.779 5681.299 9278.695 H₂ 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 4.62 11498.227 88368.477 CO₂ 0 0 53333.098 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 O₂ 0 0 18333.252 0 0 0 0 0 N₂ 0 0 88166.278 0 0 0 0 0 CaCl₂ 134573.943 80.499 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 CaCO₃ 0 121289.059 0 0 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 H₂O 0 0 0.039 1 1 1 0.331 0.095 H₂ 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 0.669 0.905 CO₂ 0 0 0.321 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 O₂ 0 0 0.11 0 0 0 0 0 N₂ 0 0 0.53 0 0 0 0 0 CaCl₂ 1 0.001 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 CaCO₃ 0 0.999 0 0 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 H₂O 0 0 11.441 511.008 186.372 186.376 10 16.332 H₂ 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0.004 10 76.854 CO₂ 0 0 38.427 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 O₂ 0 0 18.168 0 0 0 0 0 N₂ 0 0 99.8 0 0 0 0 0 CaCl₂ 38.45 0.023 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 CaCO₃ 0 38.427 0 0 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0

TABLE 3b Mass and Energy Accounting for Case 1 Simulation. Process Stream Names MgCl₂—2W MgCl₂—4W MgCl₂—6W RECYCIE1 RX2-VENT SLURRY SOLIDS-1 SOLIDS-2 VAPOR Temperature ° C. 125 100 104 95 95 95 160 130 160 Pressure psia 16.166 16.166 14.696 14.7 14.7 14.7 22.044 14.696 22.044 Mass VFrac 0 0 0 0 1 0 0 0 1 Mass SFrac 1 1 1 0.998 0 0.999 1 1 0 Mass Flow tonne/year 385672.688 491563.087 597446.583 598447.468 106499.178 719817.026 332737.843 235090.671 70114.371 Volume Flow gal/min 39.902 39.902 116.892 147.062 56469.408 167.321 39.902 43.473 42506.729 Enthalpy MW −117.767 −175.272 −230.554 −231.312 0.241 −277.487 −88.626 −71.431 −25.379 Density lb/cuft 303.274 386.542 160.371 127.684 0.059 134.984 261.649 169.678 0.052 H₂O 0 0 0 1000 0 1000 0 0 58620.764 H₂ 0 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 0 0 11493.607 CO₂ 0 0 0 0 0.532 0 0 0 0 CO 0 0 0 0 0 0 0 0 0 O₂ 0 0 0 0.165 18333.088 0.165 0 0 0 N₂ 0 0 0 0.72 88165.558 0.72 0 0 0 CaCl₂ 0 0 0 0 0 80.499 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 121289.059 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 49037.72 0 MgCl₂*W 0 0 0 0 0 0 332737.843 0 0 MgCl₂*2W 385662.96 0 0 0 0 0 0 0 0 MgCl₂*4W 0 491563.087 0 0 0 0 0 0 0 MgCl₂*6W 0 0 597446.583 597446.583 0 597446.583 0 0 0 Mg(OH)Cl 9.728 0 0 0 0 0 0 186052.951 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 0 H₂O 0 0 0 0.002 0 0.001 0 0 0.836 H₂ 0 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 0 0 0.164 CO₂ 0 0 0 0 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 0 O₂ 0 0 0 0 0.172 0 0 0 0 N₂ 0 0 0 0 0.828 0 0 0 0 CaCl₂ 0 0 0 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 0.168 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0.209 0 MgCl₂*W 0 0 0 0 0 0 1 0 0 MgCl₂*2W 1 0 0 0 0 0 0 0 0 MgCl₂*4W 0 1 0 0 0 0 0 0 0 MgCl₂*6W 0 0 1 0.998 0 0.83 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 0.791 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 0 H₂O 0 0 0 1.76 0 1.76 0 0 103.182 H₂ 0 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 0 0 9.996 CO₂ 0 0 0 0 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 0 O₂ 0 0 0 0 18.168 0 0 0 0 N₂ 0 0 0 0.001 99.799 0.001 0 0 0 CaCl₂ 0 0 0 0 0 0.023 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 38.427 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 16.332 0 MgCl₂*W 0 0 0 0 0 0 93.186 0 0 MgCl₂*2W 93.182 0 0 0 0 0 0 0 0 MgCl₂*4W 0 93.186 0 0 0 0 0 0 0 MgCl₂*6W 0 0 93.186 93.186 0 93.186 0 0 0 Mg(OH)Cl 0.004 0 0 0 0 0 0 76.854 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 0

Example 3 Process Simulation of Magnesium Ion Catalyzed Capture CO₂ from Flue Gas Using CaCl₂ to Form CaCO₃

Part of the defined parameters includes the process flow diagram shown in FIG. 7. Results from the simulation suggest that it is efficient to heat a MgCl₂.6H₂O stream to form Mg(OH)Cl in two separate dehydration reactions, each in their own chambers followed by a decomposition reaction, also in its own chamber to form Mg(OH)Cl and HCl, i.e. a total of three chambers. The Mg(OH)Cl is reacted with H₂O to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂.6H₂O formed is recycled to the first reactor to begin the process again. This process is not limited to any particular source for CaCl₂. For example, it may be obtained from reacting calcium silicate with HCl to yield CaCl₂.

Constraints and parameters specified for this simulation include:

-   -   The reactions were run at 100% efficiencies with no losses. The         simulations can be modified when pilot runs determine the         reaction efficiencies.     -   Simulations did not account for impurities in the CaCl₂ feed         stock or in any make-up MgCl₂ required due to losses from the         system.

The results of this simulation indicate a preliminary net energy consumption of 4862 kwh/tonne CO₂. Table 4 provides mass and energy accounting for the various streams of the simulated process. Each stream corresponds to the stream in FIG. 7.

The process consists of two primary reactors and one solids filtration section. The first reactor heats MgCl₂.6H₂O causing it to break down into a HCl/H₂O vapor stream and a solid stream of Mg(OH)Cl. The HCl/H₂O vapor stream is sent to a heat exchanger to recover extra heat. The Mg(OH)₂ formed from the Mg(OH)Cl is sent to reactor 2 for further processing. Chemical reaction(s) occurring in this reactor include the following: MgCl₂.6H₂O+Δ→Mg(OH)Cl+5H₂O↑+HCl↑  (35) 2 Mg(OH)Cl(aq)→Mg(OH)₂+MgCl₂  (36)

A CaCl₂ solution and a flue gas stream are added to the Mg(OH)₂ in reactor 2. This reaction forms CaCO₃, MgCl₂ and water. The CaCO₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. Chemical reaction(s) occurring in this reactor include the following: Mg(OH)₂+CaCl₂+CO₂→CaCO₃↓(s)+MgCl₂+H₂O  (37)

The primary feeds to this process are CaCl₂, flue gas (CO₂) and water. MgCl₂ in the system is used, reformed and recycled. The only MgCl₂ make-up required is to replace small amounts that leave the system with the CaCO₃ product, and small amounts that leave with the HCl/water product.

This process is a net energy user. The amount of energy is under investigation and optimization. There is cross heat exchange to recover the heat in high temperature streams to preheat the feed streams.

The steps for this process (Case 2) are summarized below:

CASE 2 2 STEP Dehydration then Decomposition Hexahydrate is dehydrated in 2 separate chambers. Step 1 hex to tetra, Step 2 tetra to di. Di-hydrate is decomposed into 100% Mg(OH)Cl. CO₂ Absorbed 53333 MTPY CaCl₂ 134574 MTPY HCl Dry 88368 MTPY CaCO₃ 105989 MTPY Hexahydrate recycled 492737 MTPY HEX TO TETRA (100° C.) 1445 kWh/tonne CO₂ TETRA TO DI (125° C.) 1774 kWh/tonne CO₂ DI-HYDRATE DEHYDRATION & DECOMPOSITION 1790 kWh/tonne CO₂ TO 100% Mg(OH)Cl (130° C.) YEILDS 66% HCl VAPOR NO CARRIER MgCl₂ = BETTER OVERALL EFFICIENCY NO USE OF HCl PP 0.9 Heat Recovery 148 kWh/tonne CO₂ from 28% HCl vapor TOTAL 4862 kWh/tonne CO₂

TABLE 4a Mass and Energy Accounting for Case 2 Simulation. Process Stream Names 5 7 8 CaCl₂ CaCO₃ Temperature ° C. 98 114.1 101 25 95 Pressure psia 14.696 14.696 14.696 14.7 14.7 Mass VFrac 0 0 1 0 0 Mass SFrac 1 1 0 1 1 Mass Flow 492736.693 405410.587 306683.742 134573.943 121369.558 tonne/year Volume Flow 96.405 32.909 224394.519 30.929 22.514 gal/min Enthalpy MW −190.292 −144.291 −98.931 −30.599 −46.174 Density lb/cuft 160.371 386.542 0.043 136.522 169.146 H₂O 0 0 218315.265 0 0 H₂ 0 0 0 0 0 Cl₂ 0 0 0 0 0 HCl 0 0 88368.477 0 0 CO₂ 0 0 0 0 0 CO 0 0 0 0 0 O₂ 0 0 0 0 0 N₂ 0 0 0 0 0 CaCl₂ 0 0 0 134573.943 80.499 Ca(OH)₂ 0 0 0 0 0 CaCO₃ 0 0 0 0 121289.059 MgCO₃ 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂*4W 0 405410.587 0 0 0 MgCl₂*6W 492736.693 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 MgO 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 H₂O 0 0 0.712 0 0 H₂ 0 0 0 0 0 Cl₂ 0 0 0 0 0 HCl 0 0 0.288 0 0 CO₂ 0 0 0 0 0 CO 0 0 0 0 0 O₂ 0 0 0 0 0 N₂ 0 0 0 0 0 CaCl₂ 0 0 0 1 0.001 Ca(OH)₂ 0 0 0 0 0 CaCO₃ 0 0 0 0 0.999 MgCO₃ 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂*4W 0 1 0 0 0 MgCl₂*6W 1 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 MgO 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 H₂O 0 0 384.27 0 0 H₂ 0 0 0 0 0 Cl₂ 0 0 0 0 0 HCl 0 0 76.854 0 0 CO₂ 0 0 0 0 0 CO 0 0 0 0 0 O₂ 0 0 0 0 0 N₂ 0 0 0 0 0 CaCl₂ 0 0 0 38.45 0.023 Ca(OH)₂ 0 0 0 0 0 CaCO₃ 0 0 0 0 38.427 MgCO₃ 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂*4W 0 76.854 0 0 0 MgCl₂*6W 76.854 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 MgO 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 Process Stream Names FLUEGAS H₂O H₂O-1 H₂O-2 HCl Vapor Temperature ° C. 40 25 100 125 130 Pressure psia 15.78 14.7 14.696 22.044 14.696 Mass VFrac 1 0 1 1 1 Mass SFrac 0 0 0 0 0 Mass Flow 166332.6 234646.82 87326.106 87329.947 132027.689 tonne/year Volume Flow 63660.018 6546.44 74598.258 53065.241 80593.954 gal/min Enthalpy MW −17.821 −118.063 −36.806 −36.675 −25.187 Density lb/cuft 0.082 1.125 0.037 0.052 0.051 H₂O 6499.971 234646.82 87326.106 87326.106 43663.053 H₂ 0 0 0 0 0 Cl₂ 0 0 0 0 0 HCl 0 0 0 3.841 88364.636 CO₂ 53333.098 0 0 0 0 CO 0 0 0 0 0 O₂ 18333.252 0 0 0 0 N₂ 88166.278 0 0 0 0 CaCl₂ 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 CaCO₃ 0 0 0 0 0 MgCO₃ 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 MgO 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 H₂O 0.039 1 1 1 0.331 H₂ 0 0 0 0 0 Cl₂ 0 0 0 0 0 HCl 0 0 0 0 0.669 CO₂ 0.321 0 0 0 0 CO 0 0 0 0 0 O₂ 0.11 0 0 0 0 N₂ 0.53 0 0 0 0 CaCl₂ 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 CaCO₃ 0 0 0 0 0 MgCO₃ 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 MgO 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 H₂O 11.441 413.016 153.708 153.708 76.854 H₂ 0 0 0 0 0 Cl₂ 0 0 0 0 0 HCl 0 0 0 0.003 76.851 CO₂ 38.427 0 0 0 0 CO 0 0 0 0 0 O₂ 18.168 0 0 0 0 N₂ 99.8 0 0 0 0 CaCl₂ 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 CaCO₃ 0 0 0 0 0 MgCO₃ 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 MgO 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0

TABLE 4b Mass and Energy Accounting for Case 2 Simulation. Process Stream Names LIQUID MgCl₂—4W MgCl₂—6W RECYCLE1 RX2-VENT SLURRY SOLIDS-1 SOLIDS-2 VAPOR Temperature ° C. 94.9 100 75 95 95 95 125 130 118.1 Pressure psia 14.696 14.696 14.696 14.7 14.7 14.7 22.044 14.696 14.696 Mass VFrac 0.979 0 0 0 1 0 0 0 1 Mass SFrac 0 1 1 0.998 0 0.998 1 1 0 Mass Flow tonne/ 306683.742 405410.587 492736.693 493737.578 106499.178 615107.136 318080.64 186052.951 306683.742 year Volume Flow gal/ 215496.035 32.909 96.405 126.575 56469.408 146.834 32.909 32.909 234621.606 min Enthalpy MW −99.487 −144.553 −190.849 −190.859 0.241 −237.034 −97.128 −61.083 −98.668 Density lb/cuft 0.045 386.542 160.371 122.394 0.059 131.442 303.277 177.393 0.041 H₂O 218315.265 0 0 1000 0 1000 0 0 218315.265 H₂ 0 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 0 HCl 88368.477 0 0 0 0 0 0 0 88368.477 CO₂ 0 0 0 0 0.532 0 0 0 0 CO 0 0 0 0 0 0 0 0 0 O₂ 0 0 0 0.165 18333.088 0.165 0 0 0 N₂ 0 0 0 0.72 88165.558 0.72 0 0 0 CaCl₂ 0 0 0 0 0 80.499 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 121289.059 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 318077.568 0 0 MgCl₂*4W 0 405410.587 0 0 0 0 0 0 0 MgCl₂*6W 0 0 492736.693 492736.693 0 492736.693 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 186052.951 0 Mg(OH)₂ 0 0 0 0 0 0 3.072 0 0 MgO 0 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 0 Mass Frac H₂O 0.712 0 0 0.002 0 0.002 0 0 0.712 H₂ 0 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 0 HCl 0.288 0 0 0 0 0 0 0 0.288 CO₂ 0 0 0 0 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 0 O₂ 0 0 0 0 0.172 0 0 0 0 N₂ 0 0 0 0 0.828 0 0 0 0 CaCl₂ 0 0 0 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 0.197 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 1 0 0 MgCl₂*4W 0 1 0 0 0 0 0 0 0 MgCl₂*6W 0 0 1 0.998 0 0.801 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 1 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 0 H₂O 384.27 0 0 1.76 0 1.76 0 0 384.27 H₂ 0 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 0 HCl 76.854 0 0 0 0 0 0 0 76.854 CO₂ 0 0 0 0 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 0 O₂ 0 0 0 0 18.168 0 0 0 0 N₂ 0 0 0 0.001 99.799 0.001 0 0 0 CaCl₂ 0 0 0 0 0 0.023 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 38.427 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 76.852 0 0 MgCl₂*4W 0 76.854 0 0 0 0 0 0 0 MgCl₂*6W 0 0 76.854 76.854 0 76.854 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 76.854 0 Mg(OH)₂ 0 0 0 0 0 0 0.002 0 0 MgO 0 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 0

Example 4 Process Simulation of Magnesium Ion Catalyzed Capture CO₂ from Flue Gas Using CaCl₂ to Form CaCO₃

Part of the defined parameters include the process flow diagram shown in FIG. 8. Results from the simulation suggest that it is efficient to heat a MgCl₂.6H₂O stream to form MgO in a single chamber. The MgO is reacted with H₂O to form Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂.6H₂O formed is recycled to the first reactor to begin the process again. This process is not limited to any particular source for CaCl₂. For example, it may be obtained from reacting calcium silicate with HCl to yield CaCl₂.

Constraints and parameters specified for this simulation include:

-   -   The reactions were run at 100% efficiencies with no losses. The         simulations can be modified when pilot runs determine the         reaction efficiencies.     -   Simulations did not account for impurities in the CaCl₂ feed         stock or in any make-up MgCl₂ required due to losses from the         system.

The results of this simulation indicate a preliminary net energy consumption of 3285 kwh/tonne CO₂. Table 5 provides mass and energy accounting for the various streams of the simulated process. Each stream corresponds to the stream of FIG. 8.

The process consists of two primary reactors and one solids filtration section. The first reactor heats MgCl₂.6H₂O causing it to break down into a HCl/H₂O vapor stream and a solid stream of MgO. The HCl/H₂O vapor stream is sent to a heat exchanger to recover extra heat. The Mg(OH)₂ formed from the MgO is sent to reactor 2 for further processing. Chemical reaction(s) occurring in this reactor include the following: MgCl₂.6H₂O+Δ→MgO+5H₂O↑+2HCl↑  (38) MgO+H₂O Mg(OH)₂  (39)

A CaCl₂ solution and a flue gas stream are added to the Mg(OH)₂ in reactor 2. This reaction forms CaCO₃, MgCl₂ and water. The CaCO₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. Chemical reaction(s) occurring in this reactor include the following: Mg(OH)₂+CaCl₂+CO₂→CaCO₃↓(s)+MgCl₂+H₂O  (40)

The primary feeds to this process are CaCl₂, flue gas (CO₂) and water. MgCl₂ in the system is used, reformed and recycled. The only MgCl₂ make-up required is to replace small amounts that leave the system with the CaCO₃ product, and small amounts that leave with the HCl/water product.

This process is a net energy user. The amount of energy is under investigation and optimization. There is cross heat exchange to recover the heat in high temperature streams to preheat the feed streams.

The steps for this process (Case 3) are summarized below:

CASE 3 Combined Dehydration/Decomposition to MgO Hexahydrate is dehydrated and decomposed simultaneously at 450 C. Reactor yeilds 100% MgO. CO₂ Absorbed 53333 MTPY CaCl₂ 134574 MTPY HCl Dry 88368 MTPY CaCO₃ 105989 MTPY Hexahydrate recycled 246368 MTPY HEXAHYDRATE DEHYDRATION & DECOMPOSITION 3778 kWh/tonne CO2 TO 100% MgO (450° C.) YIELDS 44.7% HCl VAPOR RECYCLES HALF AS MUCH HEXAHYDRATE BUT NEEDS HIGH QUALITY HEAT Heat Recovery 493 kWh/tonne CO2 from 45% HCl vapor TOTAL 3285 kWh/tonne CO2

TABLE 5a Mass and Energy Accounting for Case 3 Simulation. Process Stream Names CaCl₂ CaCO₃ FLUE GAS H₂O HCl VAP MgCl₂ MgCl₂—6W Temperature ° C. 25 95 104 25 120 353.8 104 Pressure psia 14.7 14.7 15.78 14.7 14.696 14.7 14.7 Mass VFrac 0 0 1 0 1 0 0 Mass SFrac 1 1 0 0 0 1 1 Mass Flow tonne/year 134573.943 121369.558 166332.6 125489.188 197526.11 246368.347 246368.347 Volume Flow gal/min 30.929 22.514 76673.298 3501.038 137543.974 48.203 48.203 Enthalpy MW −30.599 −46.174 −17.479 −63.14 −52.762 −92.049 −95.073 Density lb/cuft 136.522 169.146 0.068 1.125 0.045 160.371 160.371 H₂O 0 0 6499.971 125489.188 109157.633 0 0 H₂ 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 HCl 0 0 0 0 88368.477 0 0 CO₂ 0 0 53333.098 0 0 0 0 CO 0 0 0 0 0 0 0 O₂ 0 0 18333.252 0 0 0 0 N₂ 0 0 88166.278 0 0 0 0 CaCl₂ 134573.943 80.499 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 CaCO₃ 0 121289.059 0 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 246368.347 246368.347 Mg(OH)Cl 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 H₂O 0 0 0.039 1 0.553 0 0 H₂ 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 HCl 0 0 0 0 0.447 0 0 CO₂ 0 0 0.321 0 0 0 0 CO 0 0 0 0 0 0 0 O₂ 0 0 0.11 0 0 0 0 N₂ 0 0 0.53 0 0 0 0 CaCl₂ 1 0.001 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 CaCO₃ 0 0.999 0 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 1 1 Mg(OH)Cl 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 H₂O 0 0 11.441 220.881 192.135 0 0 H₂ 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 HCl 0 0 0 0 76.854 0 0 CO₂ 0 0 38.427 0 0 0 0 CO 0 0 0 0 0 0 0 O₂ 0 0 18.168 0 0 0 0 N₂ 0 0 99.8 0 0 0 0 CaCl₂ 38.45 0.023 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 CaCO₃ 0 38.427 0 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 38.427 38.427 Mg(OH)Cl 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0

TABLE 5b Mass and Energy Accounting for Case 3 Simulation. Process Stream Names Mg(OH)Cl1 Mg(OH)Cl2 RECYCLE1 RECYCLE2 RECYCLE3 RX2-VENT SLURRY VAPOR VENT Temperature ° C. 450 100 95 140 140 95 95 450 140 Pressure psia 14.696 14.696 14.7 14.7 14.7 14.7 14.7 14.696 14.7 Mass VFrac 0 0 0 0.004 0 1 0 1 1 Mass SFrac 1 1 0.996 0.996 1 0 0.997 0 0 Mass Flow tonne/year 48842.237 48842.237 247369.231 247369.231 246368.347 106499.178 368738.79 197526.11 1000.885 Volume Flow gal/min 6.851 6.851 78.372 994.232 48.203 56469.408 98.632 252994.849 946.03 Enthalpy MW −22.38 −23 −95.676 −95.057 −94.638 0.241 −141.851 −49.738 −0.419 Density lb/cuft 223.695 223.695 99.036 7.807 160.371 0.059 117.304 0.024 0.033 H₂O 0 0 1000 1000 0 0 1000 109157.633 1000 H₂ 0 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 0 88368.477 0 CO₂ 0 0 0 0 0 0.532 0 0 0 CO 0 0 0 0 0 0 0 0 0 O₂ 0 0 0.165 0.165 0 18333.088 0.165 0 0.165 N₂ 0 0 0.72 0.72 0 88165.558 0.72 0 0.72 CaCl₂ 0 0 0 0 0 0 80.499 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 0 121289.059 0 0 MgCO₃ 0 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0 246368.347 246368.347 246368.347 0 246368.347 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 0 MgO 48842.237 48842.237 0 0 0 0 0 0 0 H₂O 0 0 0.004 0.004 0 0 0.003 0.553 0.999 H₂ 0 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 0 0.447 0 CO₂ 0 0 0 0 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 0 O₂ 0 0 0 0 0 0.172 0 0 0 N₂ 0 0 0 0 0 0.828 0 0 0.001 CaCl₂ 0 0 0 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 0 0.329 0 0 MgCO₃ 0 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0.996 0.996 1 0 0.668 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 0 MgO 1 1 0 0 0 0 0 0 0 H₂O 0 0 1.76 1.76 0 0 1.76 192.135 1.76 H₂ 0 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 0 76.854 0 CO₂ 0 0 0 0 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 0 O₂ 0 0 0 0 0 18.168 0 0 0 N₂ 0 0 0.001 0.001 0 99.799 0.001 0 0.001 CaCl₂ 0 0 0 0 0 0 0.023 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 0 38.427 0 0 MgCO₃ 0 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0 38.427 38.427 38.427 0 38.427 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 0 MgO 38.427 38.427 0 0 0 0 0 0 0

Example 5 Process Simulation of Magnesium Ion Catalyzed Capture CO₂ from Flue Gas Using CaCl₂ to Form CaCO₃

Part of the defined parameters include the process flow diagram shown in FIG. 9. Results from the simulation suggest that it is efficient to heat a MgCl₂.6H₂O stream to form Mg(OH)Cl in a single chamber. The Mg(OH)Cl is reacted with H₂O to form MgCl₂ and Mg(OH)₂, which then reacts with a saturated CaCl₂/H₂O solution and CO₂ from the flue gas to form CaCO₃, which is filtered out of the stream. The resulting MgCl₂.6H₂O formed is recycled to the first reactor to begin the process again. This process is not limited to any particular source for CaCl₂. For example, it may be obtained from reacting calcium silicate with HCl to yield CaCl₂.

Constraints and parameters specified for this simulation include:

-   -   The reactions were run at 100% efficiencies with no losses. The         simulations can be modified when pilot runs determine the         reaction efficiencies.     -   Simulations did not account for impurities in the CaCl₂ feed         stock or in any make-up MgCl₂ required due to losses from the         system.

The results of this simulation indicate a preliminary net energy consumption of 4681 kwh/tonne CO₂. Table 6 provides mass and energy accounting for the various streams of the simulated process. Each stream corresponds to the stream of FIG. 9.

The process consists of two primary reactors and one solids filtration section. The first reactor heats MgCl₂.6H₂O causing it to break down into a HCl/H₂O vapor stream and a solid stream of Mg(OH)Cl. The HCl/H₂O vapor stream is sent to a heat exchanger to recover extra heat. The Mg(OH)₂ formed from the Mg(OH)Cl is sent to reactor 2 for further processing. Chemical reaction(s) occurring in this reactor include the following: MgCl₂.6H₂O+Δ→Mg(OH)Cl+5H₂O↑+HCl↑  (41) 2Mg(OH)Cl(aq)→Mg(OH)₂+MgCl₂  (42)

A CaCl₂ solution and a flue gas stream are added to the Mg(OH)₂ in reactor 2. This reaction forms CaCO₃, MgCl₂ and water. The CaCO₃ precipitates and is removed in a filter or decanter. The remaining MgCl₂ and water are recycled to the first reactor. Additional water is added to complete the water balance required by the first reactor. Chemical reaction(s) occurring in this reactor include the following: Mg(OH)₂+CaCl₂+CO₂→CaCO₃↓(s)+MgCl₂+H₂O  (43)

The primary feeds to this process are CaCl₂, flue gas (CO₂) and water. MgCl₂ in the system is used, reformed and recycled. The only MgCl₂ make-up required is to replace small amounts that leave the system with the CaCO₃ product, and small amounts that leave with the HCl/water product.

This process is a net energy user. The amount of energy is under investigation and optimization. There is cross heat exchange to recover the heat in high temperature streams to preheat the feed streams.

The steps for this process (Case 4) are summarized below:

CASE 4 Combined Dehydration/Decomposition to Mg(OH)Cl Hexahydrate is dehydrated and decomposed simultaneously at 250° C. Reactor yields 100% Mg(OH)Cl. CO₂ Absorbed 53333 MTPY CaCl₂ 134574 MTPY HCl Dry 88368 MTPY CaCO₃ 105989 MTPY Hexahydrate recycled 492737 MTPY DEHYDRATION & DECOMPOSITION 5043 kWh/tonne CO2 TO 100% Mg(OH)Cl (250° C.) YEILDS 28.8% HCl VAPOR 2.2 MW Heat Recovery 361 kWh/tonne CO2 from 28% HCl vapor TOTAL 4681 kWh/tonne CO2

TABLE 6a Mass and Energy Accounting for Case 4 Simulation. Process Stream Names CaCl₂ CaCO₃ FLUEGAS H₂O HCIVAP MgCl₂ MgCl₂—6W Mg(OH)Cl1 Temperature ° C. 25 95 104 25 120 188 104 250 Pressure psia 14.7 14.7 15.78 14.7 14.696 14.7 14.7 14.696 Mass VFrac 0 0 1 0 1 0 0 0 Mass SFrac 1 1 0 0 0 1 1 1 Mass Flow tonne/year 134573.943 121369.558 166332.6 234646.82 306683.742 492736.693 492736.693 186052.951 Volume Flow gal/min 30.929 22.514 76673.298 6546.44 235789.67 96.405 96.405 32.909 Enthalpy MW −30.599 −46.174 −17.479 −118.063 −98.638 −188.114 −190.147 −60.661 Density lb/cuft 136.522 169.146 0.068 1.125 0.041 160.371 160.371 177.393 H₂O 0 0 6499.971 234646.82 218315.265 0 0 0 H₂ 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 HCl 0 0 0 0 88368.477 0 0 0 CO₂ 0 0 53333.098 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 O₂ 0 0 18333.252 0 0 0 0 0 N₂ 0 0 88166.278 0 0 0 0 0 CaCl₂ 134573.943 80.499 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 CaCO₃ 0 121289.059 0 0 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 492736.693 492736.693 0 Mg(OH)Cl 0 0 0 0 0 0 0 186052.951 Mg(OH)₂ 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 H₂O 0 0 0.039 1 0.712 0 0 0 H₂ 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0.288 0 0 0 CO₂ 0 0 0.321 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 O₂ 0 0 0.11 0 0 0 0 0 N₂ 0 0 0.53 0 0 0 0 0 CaCl₂ 1 0.001 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 CaCO₃ 0 0.999 0 0 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 1 1 0 Mg(OH)Cl 0 0 0 0 0 0 0 1 Mg(OH)₂ 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 H₂O 0 0 11.441 413.016 384.27 0 0 0 H₂ 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 HCl 0 0 0 0 76.854 0 0 0 CO₂ 0 0 38.427 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 O₂ 0 0 18.168 0 0 0 0 0 N₂ 0 0 99.8 0 0 0 0 0 CaCl₂ 38.45 0.023 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 CaCO₃ 0 38.427 0 0 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 76.854 76.854 0 Mg(OH)Cl 0 0 0 0 0 0 0 76.854 Mg(OH)₂ 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0

TABLE 6b Mass and Energy Accounting for Case 4 Simulation. Process Stream Names Mg(OH)Cl₂ RECYCLE1 RECYCLE2 RECYCLE3 RX2-VENT SLURRY VAPOR VENT Temperature ° C. 100 95 113.8 113.8 95 95 250 113.8 Pressure psia 14.696 14.7 14.7 14.7 14.7 14.7 14.696 14.7 Mass VFrac 0 0 0.002 0 1 0 1 1 Mass SFrac 1 0.998 0.998 1 0 0.998 0 0 Mass Flow tonne/year 186052.95 493737.58 493737.58 492736.69 106499.18 615107.14 306683.74 1000.89 Volume Flow gal/min 32.909 126.575 982.405 96.405 56469.408 146.834 313756.5 886 Enthalpy MW −61.189 −190.859 −190.331 −189.91 0.241 −237.034 −96.605 −0.421 Density lb/cuft 177.393 122.394 15.769 160.371 0.059 131.442 0.031 0.035 H₂O 0 1000 1000 0 0 1000 218315.27 1000 H₂ 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 88368.477 0 CO₂ 0 0 0 0 0.532 0 0 0 CO 0 0 0 0 0 0 0 0 O₂ 0 0.165 0.165 0 18333.088 0.165 0 0.165 N₂ 0 0.72 0.72 0 88165.558 0.72 0 0.72 CaCl₂ 0 0 0 0 0 80.499 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 121289.06 0 0 MgCO₃ 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 492736.69 492736.69 492736.69 0 492736.69 0 0 Mg(OH)Cl 186052.95 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 H₂O 0 0.002 0.002 0 0 0.002 0.712 0.999 H₂ 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 0.288 0 CO₂ 0 0 0 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 O₂ 0 0 0 0 0.172 0 0 0 N₂ 0 0 0 0 0.828 0 0 0.001 CaCl₂ 0 0 0 0 0 0 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 0.197 0 0 MgCO₃ 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 0.998 0.998 1 0 0.801 0 0 Mg(OH)Cl 1 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 H₂O 0 1.76 1.76 0 0 1.76 384.27 1.76 H₂ 0 0 0 0 0 0 0 0 Cl₂ 0 0 0 0 0 0 0 0 HCl 0 0 0 0 0 0 76.854 0 CO₂ 0 0 0 0 0 0 0 0 CO 0 0 0 0 0 0 0 0 O₂ 0 0 0 0 18.168 0 0 0 N₂ 0 0.001 0.001 0 99.799 0.001 0 0.001 CaCl₂ 0 0 0 0 0 0.023 0 0 Ca(OH)₂ 0 0 0 0 0 0 0 0 CaCO₃ 0 0 0 0 0 38.427 0 0 MgCO₃ 0 0 0 0 0 0 0 0 Ca(O)Cl₂ 0 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 76.854 76.854 76.854 0 76.854 0 0 Mg(OH)Cl 76.854 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0

Example 6 Road Salt Boiler: Decomposition of MgCl₂.6H₂O

FIG. 10 shows a graph of the mass percentage of a heated sample of MgCl₂.6H₂O. The sample's initial mass was approximately 70 mg and set at 100%. During the experiment, the sample's mass was measured while it was being thermally decomposed. The temperature was quickly ramped up to 150° C., and then slowly increased by 0.5° C. per minute. At approximately 220° C., the weight became constant, consistent with the formation of Mg(OH)Cl. The absence of further weight decrease indicated that almost all the water has been removed. Two different detailed decompositional mass analyses are shown in FIGS. 28 and 29, with the theoretical plateaus of different final materials shown. FIG. 30 confirms that MgO can be made by higher temperatures (here, 500° C.) than those which produce Mg(OH)Cl.

Example 7 Dissolution of Mg(OH)Cl in H₂O

A sample of Mg(OH)Cl, produced by the heated decomposition of MgCl₂.6H₂O, was dissolved in water and stirred for a period of time. Afterwards, the remaining precipitate was dried, collected and analyzed. By the formula of decomposition, the amount of Mg(OH)₂ could be compared to the expected amount and analyzed. The chemical reaction can be represented as follows: 2Mg(OH)Cl(aq)→Mg(OH)₂+MgCl₂  (44)

The solubility data for Mg(OH)₂ and MgCl₂ is as follows:

-   -   MgCl₂ 52.8 gm in 100 gm. H₂O (very soluble)     -   Mg(OH)₂ 0.0009 gm in 100 gm. H₂O (virtually insoluble)

Theoretical weight of recovered Mg(OH)₂:

Given weight of sample: 3.0136 gm.

-   -   MW Mg(OH)Cl 76.764     -   MW Mg(OH)₂ 58.32     -   Moles Mg(OH)₂ formed per mole Mg(OH)Cl=½

Expected amount of Mg(OH)₂ 2Mg(OH)Cl(aq)→Mg(OH)₂+MgCl₂ 3.016 gm*(MW Mg(OH)₂÷(MW Mg(OH)Cl*½=1.1447 gm

Precipitate collected=1.1245 gm

% of theoretical collected=(1.1447÷1.1245)*100=98.24%

Analytical data:

Next the sample of Mg(OH)₂ was sent for analysis, XRD (X-ray-diffraction) and EDS. Results are shown in FIG. 11. The top row of peaks is that of the sample, the spikes in the middle row are the signature of Mg(OH)₂ while the spikes at the bottom are those of MgO. Thus verifying that the recovered precipitate from the dissolution of Mg(OH)Cl has a signal resembling that of Mg(OH)₂.

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.9472 1.014 96.88 96.02 +/−0.23 Si—K 0.0073 2.737 1.74 1.99 +/−0.17 Cl—K 0.0127 1.570 1.38 2.00 +/−0.16 Total 100.00 100.00 Note: Results do not include elements with Z < 11 (Na). The EDS analysis reveals that very little chlorine [Cl] was incorporated into the precipitate. Note, this analysis cannot detect oxygen or hydrogen.

Example 8 Decarbonation Bubbler Experiment: Production of CaCO₃ by Reacting CO₂ with Mg(OH)₂ {or Mg(OH)Cl} and CaCl₂

Approximately 20 grams of Mg(OH)₂ was placed in a bubble column with two liters of water and CO₂ was bubbled though it for x minutes period of time. Afterwards some of the liquid was collected to which a solution of CaCl₂ was added. A precipitate immediately formed and was sent through the XRD and EDS. The chemical reaction can be represented as follows: Mg(OH)₂+CO₂+CaCl₂→CaCO₃↓+H₂O  (45) The XRD analysis (FIG. 12) coincides with the CaCO₃ signature. EDS

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.0070 2.211 2.52 1.55 +/−0.10 Al—K 0.0013 1.750 0.33 0.22 +/−0.04 Si—K 0.0006 1.382 0.12 0.09 +/−0.03 Cl—K 0.0033 1.027 0.38 0.34 +/−0.03 Ca—K 0.9731 1.005 96.64 97.80 +/−0.30 Total 100.00 100.00 Note: Results do not include elements with Z < 11(Na). The EDS analysis indicates almost pure CaCO₃ with only a 1.55% by weight magnesium impurity and almost no Chlorine from the CaCl₂.

The same test was performed, except that Mg(OH)Cl from the decomposition of MgCl₂.6H₂O was used instead of Mg(OH)₂. Although Mg(OH)Cl has half the hydroxide [OH⁻], as Mg(OH)₂ it is expected to absorb CO₂ and form precipitated CaCO₃ (PCC).

The XRD analysis (FIG. 13) coincides with the CaCO₃ signature.

EDS

Chi-sqd = 5.83 Livetime = 300.0 Sec. Standardless Analysis PROZA Correction Acc. Volt. = 20 kV Take-off Angle = 35.00 deg Number of Iterations = 3 Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.0041 2.224 1.48 0.90 +/−0.09 S—K 0.0011 1.071 0.14 0.11 +/−0.04 Ca—K 0.9874 1.003 98.38 98.98 +/−0.34 Total 100.00 100.00 Note: Results do not include elements with Z < 11 (Na). Again the results indicate almost pure CaCO₃, almost no Mg or Cl compounds.

Example 9A Rock Melter Experiment: Reaction of Olivine and Serpentine with HCl

Samples of olivine (Mg,Fe)₂SiO₄ and serpentine Mg₃Si₂O₅(OH)₄ were crushed and reacted with 6.1 molar HCl over a period of approximately 72 hours. Two sets of tests were run, the first at room temperature and the second at 70° C. These minerals have variable formulae and often contain iron. After the samples were filtered, the resulting filtrand and filtrate were dried in an oven overnight. The samples then went through XRD and EDS analysis. The filtrates should have MgCl₂ present and the filtrand should be primarily SiO₂.

Olivine Filtrate Reacted with HCl at Room Temperature

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.1960 1.451 37.06 28.45 +/−0.18 Si—K 0.0103 1.512 1.75 1.56 +/−0.11 Cl—K 0.5643 1.169 58.89 65.94 +/−0.31 Fe—K 0.0350 1.161 2.30 4.06 +/−0.22 Total 100.00 100.00 Olivine Filtrate Reacted with HCl at 70° C.

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.1172 1.684 27.39 19.74 +/−0.12 Si—K 0.0101 1.459 1.77 1.48 +/−0.07 Cl—K 0.5864 1.142 63.70 66.94 +/−0.24 Fe—K 0.0990 1.144 6.84 11.33 +/−0.21 Ni—K 0.0045 1.128 0.29 0.51 +/−0.09 Total 100.00 100.00 Note: Results do not include elements with Z < 11 (Na). Serpentine Filtrate Reacted with HCl at Room Temperature

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.1674 1.466 32.47 24.53 +/−0.15 Al—K 0.0025 1.863 0.55 0.46 +/−0.06 Si—K 0.0033 1.456 0.55 0.48 +/−0.04 Cl—K 0.6203 1.141 64.22 70.77 +/−0.27 Ca—K 0.0016 1.334 0.17 0.21 +/−0.05 Cr—K 0.0026 1.200 0.19 0.31 +/−0.07 Mn—K 0.0011 1.200 0.08 0.14 +/−0.08 Fe—K 0.0226 1.160 1.51 2.62 +/−0.10 Ni—K 0.0042 1.128 0.26 0.48 +/−0.10 Total 100.00 100.00 Note: Results do not include elements with Z < 11 (Na). Serpentine Filtrate Reacted with HCl at 70° C.

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.1759 1.455 33.67 25.59 +/−0.14 Al—K 0.0017 1.886 0.39 0.33 +/−0.06 Si—K 0.0087 1.468 1.46 1.28 +/−0.04 Cl—K 0.6014 1.152 62.46 69.27 +/−0.25 Cr—K 0.0016 1.199 0.12 0.19 +/−0.06 Fe—K 0.0268 1.161 1.78 3.11 +/−0.17 Ni—K 0.0020 1.130 0.12 0.22 +/−0.08 Total 100.00 100.00 Note: Results do not include elements with Z < 11 (Na). Note: Results do not include elements with Z < 11 (Na).

The filtrate clearly for both minerals serpentine and olivine at ambient conditions and 70° C. all illustrate the presence of MgCl₂, and a small amount of FeCl₂ in the case of olivine.

Olivine Filtrand Reacted with HCl at Room Temperature

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.2239 1.431 37.68 32.04 +/−0.14 Si—K 0.3269 1.622 53.96 53.02 +/−0.19 Cl—K 0.0140 1.658 1.87 2.32 +/−0.06 Cr—K 0.0090 1.160 0.58 1.05 +/−0.08 Mn—K 0.0013 1.195 0.08 0.16 +/−0.09 Fe—K 0.0933 1.167 5.57 10.89 +/−0.26 Ni—K 0.0045 1.160 0.25 0.52 +/−0.11 Total 100.00 100.00 Note: Results do not include elements with Z < 11 (Na). Olivine Filtrand Reacted with HCl at 70° C.

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.2249 1.461 38.87 32.86 +/−0.16 Si—K 0.3030 1.649 51.12 49.94 +/−0.21 Cl—K 0.0223 1.638 2.96 3.65 +/−0.14 Ca—K 0.0033 1.220 0.29 0.41 +/−0.05 Cr—K 0.0066 1.158 0.42 0.76 +/−0.08 Mn—K 0.0023 1.193 0.15 0.28 +/−0.10 Fe—K 0.0937 1.163 5.61 10.89 +/−0.29 Ni—K 0.0074 1.158 0.42 0.86 +/−0.13 Cu—K 0.0029 1.211 0.16 0.35 +/−0.16 Total 100.00 100.00 Note: Results do not include elements with Z < 11 (Na).

Given that the formula for olivine is (Mg,Fe)₂SiO₄, and this is a magnesium rich olivine. The raw compound has a Mg:Si ratio of 2:1. However the filtrand, that which does not pass through the filter has a (Mg+Fe:Si) ratio of (37+5.5:52) or 0.817:1. (Atom % on the chart), evidently more than 50% of the magnesium passed through the filter.

Serpentine Filtrand Reacted with HCl at Room Temperature

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.1930 1.595 37.32 30.78 +/−0.15 Si—K 0.2965 1.670 51.94 49.50 +/−0.20 Cl—K 0.0065 1.633 0.88 1.06 +/−0.06 Cr—K 0.0056 1.130 0.36 0.63 +/−0.08 Fe—K 0.1532 1.155 9.33 17.69 +/−0.31 Ni—K 0.0029 1.159 0.17 0.34 +/−0.12 Total 100.00 100.00 Note: Results do not include elements with Z < 11 (Na). Serpentine Filtrand Reacted with HCl at 70° C.

Element k-ratio ZAF (calc.) Wt % (1-Sigma) Atom % Element Wt % Err. Mg—K 0.1812 1.536 33.53 27.83 +/−0.13 Si—K 0.3401 1.593 56.49 54.18 +/−0.18 Cl—K 0.0106 1.651 1.45 1.75 +/−0.11 Cr—K 0.0037 1.142 0.24 0.43 +/−0.07 Mn—K 0.0009 1.188 0.05 0.10 +/−0.08 Fe—K 0.1324 1.159 8.05 15.35 +/−0.26 Ni—K 0.0032 1.160 0.18 0.37 +/−0.11 Total 100.00 100.00 Note: Results do not include elements with Z < 11 (Na).

Given that the formula of serpentine is (Mg,Fe)₃Si₂O₅(OH)₄ the initial 1.5:1 ratio of (Mg+Fe) to Si has been whittled down to (37+9.3:56.5)=0.898:1.

Example 9B Temperature/Pressure Simulation for Decomposition of MgCl2.6(H2O)

Pressure and temperature was varied, as shown below (Table 7) and in FIG. 14, to determine the effect this has on the equilibrium of the decomposition of MgCl₂.6(H₂O). Inputs are:

-   -   1) MgCl₂.6H₂O     -   2) CaCl₂     -   3) The temperature of the hot stream leaving the heat         exchanger (MX) labeled Mg(OH)Cl (see FIGS. 7-8).     -   4) Percentage of Solids separated in decanter.     -   5) Water needed labeled H₂O     -   6) Flue Gas.

TABLE 7 VARY 1 VARY 2 REACTOR1 REACTOR1 PARAM PARAM TEMP PRES INPUT Mg(OH)Cl MgO Q ° C. PSIA MOL/SEC MOL/SEC MOL/SEC MW kWh/tonne CO2 400 5 51.08399 25.31399 25.77001 23.63765 3883 410 5 38.427 0 38.427 19.85614 3261 420 5 38.427 0 38.427 19.87482 3264 430 5 38.427 0 38.427 19.89354 3268 440 5 38.427 0 38.427 19.9123 3271 450 5 38.427 0 38.427 19.93111 3274 400 7 76.854 76.854 0 31.37484 5153 410 7 53.24627 29.63854 23.60773 24.31186 3993 420 7 38.427 0 38.427 19.87482 3264 430 7 38.427 0 38.427 19.89354 3268 440 7 38.427 0 38.427 19.9123 3271 450 7 38.427 0 38.427 19.93111 3274 400 9 76.854 76.854 0 31.37484 5153 410 9 72.85115 68.84829 4.002853 30.20646 4961 420 9 50.2148 23.5756 26.6392 23.42411 3847 430 9 38.427 0 38.427 19.89354 3268 440 9 38.427 0 38.427 19.9123 3271 450 9 38.427 0 38.427 19.93111 3274 400 11 76.854 76.854 0 31.37484 5153 410 11 76.854 76.854 0 31.41 5159 420 11 64.78938 52.72476 12.06462 27.81251 4568 430 11 44.67748 12.50096 32.17652 21.77822 3577 440 11 38.427 0 38.427 19.9123 3271 450 11 38.427 0 38.427 19.93111 3274 400 13 76.854 76.854 0 31.37484 5153 410 13 76.854 76.854 0 31.41 5159 420 13 76.854 76.854 0 31.44515 5165 430 13 55.59535 34.3367 21.25865 25.07026 4118 440 13 38.427 0 38.427 19.9123 3271 450 13 38.427 0 38.427 19.93111 3274 400 15 76.854 76.854 0 31.37484 5153 410 15 76.854 76.854 0 31.41 5159 420 15 76.854 76.854 0 31.44515 5165 430 15 66.51322 56.17244 10.34078 28.36229 4659 440 15 46.41875 15.98351 30.43525 22.32544 3667 450 15 38.427 0 38.427 19.93111 3274 200 5 127 76.854 0 47.51946 7805 210 5 85 76.854 0 33.34109 5476 220 5 77 76.854 0 30.74184 5049 230 5 77 76.854 0 30.77702 5055 240 5 77 76.854 0 30.8122 5061 250 5 77 76.854 0 30.84739 5067 200 7 184 76.854 0 66.57309 10935 210 7 125 76.854 0 46.75184 7679 220 7 85 76.854 0 33.32609 5474 230 7 77 76.854 0 30.777 5055 240 7 77 76.854 0 30.81218 5061 250 7 77 76.854 0 30.84737 5067 200 9 297 76.854 0 89.51079 14702 210 9 165 76.854 0 60.16258 9882 220 9 113 76.854 0 42.92123 7050 230 9 78 76.854 0 31.04401 5099 240 9 77 76.854 0 30.81217 5061 250 9 77 76.854 0 30.84735 5067 200 11 473 76.854 0 136.5784 22433 210 11 205 76.854 0 73.57332 12084 220 11 142 76.854 0 52.51638 8626 230 11 98 76.854 0 38.01558 6244 240 11 77 76.854 0 30.81216 5061 250 11 77 76.854 0 30.84734 5067 200 13 684 76.854 0 192.9858 31698 210 13 303 76.854 0 91.43505 15018 220 13 170 76.854 0 62.11152 10202 230 13 119 76.854 0 44.98715 7389 240 13 83.3323 76.854 0 33.00459 5421 250 13 76.854 76.854 0 30.84733 5067 200 15 930.5287 76.854 0 258.7607 42502 210 15 422.9236 76.854 0 123.7223 20322 220 15 198.7291 76.854 0 71.70666 11778 230 15 139.6567 76.854 0 51.95871 8534 240 15 98.51739 76.854 0 38.14363 6265 250 15 76.854 76.854 0 30.84733 5067

Examples 10-21

The following remaining examples are concerned with obtaining the necessary heat to perform the decomposition reaction using waste heat emissions from either coal or natural gas power plants. In order to obtain the necessary heat from coal flue gas emissions, the heat source may be located prior to the baghouse where the temperature ranges from 320-480° C. in lieu of the air pre-heater. See Reference: pages 11-15 of “The structural design of air and gas ducts for power stations and industrial Boiler Applications,” Publisher: American Society of Civil Engineers (August 1995), which is incorporated by reference herein in its entirety. Open cycle natural gas plants have much higher exhaust temperatures of 600° C. See Reference: pages 11-15 of “The structural design of air and gas ducts for power stations and industrial Boiler Applications,” Publisher: American Society of Civil Engineers (August 1995), which is incorporated by reference herein in its entirety. Additionally, the decomposition reaction of MgCl₂.6H₂O may also run in two different modes, complete decomposition to MgO or a partial decomposition to Mg(OH)Cl. The partial decomposition to Mg(OH)Cl requires in some embodiments a temperature greater than 180° C. whereas the total decomposition to MgO requires in some embodiments a temperature of 440° C. or greater.

Additionally the incoming feed to the process can be represented as a continuum between 100% Calcium Silicate (CaSiO₃) and 100% Magnesium Silicate (MgSiO₃) with Diopside (MgCa(SiO₃)₂) (or a mixture of CaSiO₃ and MgSiO₃ in a 1:1 molar ratio) representing an intermediate 50% case. For each of these cases the resulting output will range in some embodiments from calcium carbonate (CaCO₃) to magnesium carbonate (MgCO₃) with Dolomite CaMg(CO₃)₂ representing the intermediate case. The process using 100% calcium silicate is the Ca—Mg process used in all of the previously modeled embodiments. It is also important to note that the 100% magnesium silicate process uses no calcium compounds; whereas the 100% calcium silicate incoming feed process does use magnesium compounds, but in a recycle loop, only makeup magnesium compounds are required.

Further details regarding the Ca—Mg, Mg only, Diopside processes, for example, using complete and partial decomposition of hydrated MgCl₂ to MgO and Mg(OH)Cl, respectively, are depicted below.

I) Ca—Mg Process

Overall reaction CaSiO₃+CO₂→CaCO₃+SiO₂

-   -   a) Full decomposition (“the CaSiO₃—MgO process”):         MgCl₂.6H₂O+Δ→MgO+5H₂O↑+2HCl↑  1)         -   A thermal decomposition reaction.             2HCl(aq)+CaSiO₃→CaCl₂(aq)+SiO₂↓+H₂O  2)         -   A rock melting reaction.         -   Note 5H₂O will be present per 2 moles of HCl during the             reaction.             MgO+CaCl₂(aq)+CO₂→CaCO₃↓+MgCl₂(aq)  3)         -   Some versions of this equation use Mg(OH)₂ which is formed             from MgO and H₂O.             MgCl₂(aq)+6H₂O→MgCl₂.6H₂O  4)         -   Regeneration of MgCl₂.6H₂O, return to #1.     -   b) Partial decomposition (“the CaSiO₃—Mg(OH)Cl process”):         2×[MgCl₂.6H₂O+Δ→Mg(OH)Cl+5H₂O↓+HCl↑]  1)         -   Thermal decomposition.         -   Twice as much MgCl₂.6H₂O is needed to trap the same amount             of CO₂.             2HCl(aq)+CaSiO₃→CaCl₂(aq)+SiO₂↓+H₂O  2)         -   Rock melting reaction.             2Mg(OH)Cl+CaCl₂(aq)+CO₂→CaCO₃↓+2MgCl₂(aq)+H₂O  3)         -   CO₂ capture reaction             2MgCl₂+12H₂O→2MgCl₂.6H₂O  4)         -   Regeneration of MgCl₂.6H₂O, return to #1.             II) Mg Only Process

Overall reaction MgSiO₃+CO₂→>MgCO₃+SiO₂

-   -   c) Full decomposition (“the MgSiO₃—MgO process”)         2HCl(aq)+MgSiO₃+(x−1)H₂O→MgCl₂+SiO₂ ↓+xH₂O  1)         -   Rock melting reaction.             MgCl₂ .xH₂O+Δ↓MgO+(x−1)H₂O↑+2HCl↑  2)         -   Thermal decomposition reaction.         -   Note “x−1” moles H₂O will be produced per 2 moles of HCl.             MgO+CO₂→MgCO₃  3)         -   CO₂ capture reaction.

Note, in this embodiment no recycle of MgCl₂ is required. The value of x, the number of waters of hydration is much lower than 6 because the MgCl₂ from the rock melting reaction is hot enough to drive much of the water into the vapor phase. Therefore the path from the rock melting runs at steady state with “x” as modeled with a value of approximately 2.

-   -   d) Partial decomposition (“the MgSiO₃—Mg(OH)Cl process”)         2HCl(aq)+MgSiO₃→MgCl₂+SiO₂↓+H₂O  1)         -   Rock melting reaction.         -   Note “x−1” H₂O will be present per mole of HCl during the             reaction.             2×[MgCl₂ .xH₂O+Δ→Mg(OH)Cl+(x−1)H₂O↑+HCl↑]  2)         -   Decomposition.         -   Twice as much MgCl₂.(x−1)H₂O is needed to trap the same             amount of CO₂.             2Mg(OH)Cl+CO₂→MgCO₃↓+MgCl₂+H₂O  3)         -   CO₂ capture reaction.             MgCl₂(aq)+6H₂O→MgCl₂.6H₂O  4)         -   Regenerate MgCl₂.6H₂O, Return to #1.

Note, in this embodiment half of the MgCl₂ is recycled. The value of x, the number of waters of hydration is somewhat lower than 6 because half of the MgCl₂ is from the rock melting reaction which is hot enough to drive much of the water into the vapor phase and the remaining half is recycled from the absorption column. Therefore the number of hydrations for the total amount of MgCl₂ at steady state will have a value of approximately 4, being the average between the MgCl₂.6H₂O and MgCl₂.2H₂O.

III) Diopside or Mixed process:

Note diopside is a mixed calcium and magnesium silicate and dolomite is a mixed calcium and magnesium carbonate.

Overall reaction: ½CaMg(SiO₃)₂+CO₂→½CaMg(CO₃)₂+SiO₂

-   -   e) Full decomposition (“the Diopside-MgO process”):         MgCl₂.6H₂O+Δ→MgO+5H₂O↑+2HCl↑  1)         -   Thermal decomposition.             HCl+½CaMg(SiO₃)₂→½CaCl₂+½MgSiO₃↓+½SiO₂↓+½H₂O  2)         -   First rock melting reaction.             HCl+½MgSiO₃→½MgCl₂+½SiO₂↑+½H₂O  3)         -   Second rock melting reaction. The MgCl₂ returns to #1.             MgO+½CaCl₂+CO₂→½CaMg(CO₃)₂↓+½MgCl₂  4)             ½MgCl₂+3H₂O→½MgCl₂.6H2O  5)         -   Regenerate MgCl₂.6H₂O, return to #1.     -   f) Partial decomposition (“the Diopside-Mg(OH)Cl process”):         2×[MgCl₂.6H₂O+Δ→Mg(OH)Cl+5H₂O↑+HCl↑]  1)         -   Thermal decomposition.         -   Twice as much MgCl₂.6H₂O is needed to trap the same amount             of CO₂.             HCl+½CaMg(SiO₃)₂→½CaCl₂+½MgSiO₃↓+½SiO₂↓+½H₂O  2)         -   First rock melting reaction.             HCl+½MgSiO₃→½MgCl₂+½SiO₂↑+½H₂O  3)         -   Second rock melting reaction. Here the MgCl₂ returns to #1.             2Mg(OH)Cl+½CaCl₂+CO₂→½CaMg(CO₃)₂↓+ 3/2MgCl₂  4)H₂O             3/2MgCl₂+9H₂O→ 3/2MgCl₂.6H₂O  5)         -   Regenerate MgCl₂.6H₂O, return to #1

TABLE 9 Summary of Processes Detailed mass and Flue gas Temp. % CO₂ of flue energy balance of Example Process source ° C.¹ gas² each process stream 10 CaSiO₃—Mg(OH)Cl Coal 320-550 7.2%-18% Table 14 11 CaSiO₃—Mg(OH)Cl Nat. gas 600 7.2%-18% Table 14 12 CaSiO₃—MgO Coal 550 7.2%-18% Table 15 13 CaSiO₃—MgO Nat. gas 600 7.2%-18% Table 15 14 MgSiO₃—Mg(OH)Cl Coal 320-550 7.2%-18% Table 16 15 MgSiO₃—Mg(OH)Cl Nat. gas 600 7.2%-18% Table 16 16 MgSiO₃—MgO Coal 550 7.2%-18% Table 17 17 MgSiO₃—MgO Nat. gas 600 7.2%-18% Table 17 18 Diopside- Coal 320-550 7.2%-18% Table 18 Mg(OH)Cl 19 Diopside- Nat. gas 600 7.2%-18% Table 18 Mg(OH)Cl 20 Diopside-MgO Coal 550 7.2%-18% Table 19 21 Diopside-MgO Nat. gas 600 7.2%-18% Table 19 ¹The temperature range of 320-550° C. includes models run at 320, 360, 400, 440 and 550° C. respectively. ²The CO₂ percentage of flue gas 7.2%-18% includes models run at 7.2%, 10%, 14% and 18% respectively. Calcium Silicate Process:

The CaSiO₃—MgO and CaSiO₃—Mg(OH)Cl decomposition processes are further divided into two stages, the first step consists of a dehydration reaction where MgCl₂.6H₂O is converted to MgCl₂.2H₂O+4H₂O and the second step in which the MgCl₂.2H₂O is converted to Mg(OH)Cl+HCl+H₂O if partial decomposition is desired or required and MgO+2HCl+H₂O if total decomposition is desired or required. FIG. 15 describes a layout of this process.

Magnesium Silicate Process:

The MgSiO₃—MgO and MgSiO₃—Mg(OH)Cl processes consists of a one chamber decomposition step in which the HCl from the decomposition chamber reacts with MgSiO₃ in the rock-melting reactor and the ensuing heat of reaction leaves the MgCl₂ in the dihydrate form MgCl₂.2H₂O as it leaves the rock-melting chamber in approach to the decomposition reactor where it is converted to either MgO or Mg(OH)Cl as described earlier. This process may be preferred if calcium silicates are unavailable. The HCl emitted from the decomposition reacts with MgSiO₃ to form more MgCl₂. The magnesium silicate process follows a different path from the calcium. The process starts from the “rock melting reaction HCl+silicate”, and then moves to the “decomposition reaction (MgCl₂+heat),” and lastly the absorption column. In the calcium silicate process, all the magnesium compounds rotate between the decomposition reaction and the absorption reaction. FIG. 16 describes the layout of this process.

Mixed Magnesium and Calcium Silicate “Diopside” Process:

The intermediate process Diopside-MgO and Diopside-Mg(OH)Cl also involve a two stage decomposition consisting of the dehydration reaction MgCl₂.6H₂O+Δ→MgCl₂.2H₂O+4H₂O followed by the decomposition reaction MgCl₂.2H₂O+Δ→MgO+2HCl+H₂O (full decomposition) or MgCl₂.2H₂O+Δ→Mg(OH)Cl+HCl+H₂O partial decomposition. FIG. 17 describes a layout of this process.

The ensuing HCl from the decomposition then reacts with the Diopside CaMg(SiO₃)₂ in a two step “rock melting reaction.” The first reaction creates CaCl₂ through the reaction 2HCl+CaMg(SiO₃)₂→CaCl₂(aq)+MgSiO₃↓+SiO₂↓+H₂O. The solids from the previous reaction are then reacted with HCl a second time to produce MgCl₂ through the reaction MgSiO₃+2HCl→MgCl₂+SiO₂↓+H₂O. The CaCl₂ from the first rock melter is transported to the absorption column and the MgCl₂ from the second rock melter is transported to the decomposition reactor to make Mg(OH)Cl or MgO.

Basis of the Reaction:

All of these examples assume 50% CO₂ absorption of a reference flue gas from a known coal fired plant of interest. This was done to enable a comparison between each example. The emission flow rate of flue gas from this plant is 136,903,680 tons per year and the CO₂ content of this gas is 10% by weight. This amount of CO₂ is the basis for examples 10 through 21 which is:

Amount of CO₂ present in the flue gas per year: 136,903,680 tons per year*10%=13,690,368 tons per year

Amount of CO₂ absorbed per year. 13,690,368 tons per year*50%=6,845,184 tons per year of CO₂.

Since the amount of CO₂ absorbed is a constant, the consumption of reactants and generation of products is also a constant depending on the reaction stoichiometry and molecular weight for each compound.

For all the examples of both the CaSiO₃—MgO and the CaSiO₃—Mg(OH)Cl process (examples 10-13) the overall reaction is: CaSiO₃+CO₂→CaCO₃+SiO₂

For all the examples of both the MgSiO₃—MgO and the MgSiO₃—Mg(OH)Cl process (examples 14-17) the overall reaction is: MgSiO₃+CO₂→MgCO₃+SiO₂

For all the examples of both the Diopside-MgO and the Diopside-Mg(OH)Cl process (examples 18-21) the overall reaction is: ½CaMg(SiO₃)₂+CO₂→½CaMg(CO₃)₂+SiO₂

The Aspen model enters the required inputs for the process and calculates the required flue gas to provide the heat needed for the decomposition reaction to produce the carbon dioxide absorbing compounds MgO, Mg(OH)₂ or Mg(OH)Cl. This flue gas may be from a natural gas or a coal plant and in the case of coal was tested at a range of temperatures from 320° C. to 550° C. This flue gas should not be confused with the reference flue gas which was used a standard to provide a specific amount of CO₂ removal for each example. A process with a higher temperature flue gas would typically require a lesser amount of flue gas to capture the same amount of carbon dioxide from the basis. Also a flue gas with a greater carbon dioxide concentration would typically result in greater amount of flue gas needed to capture the carbon dioxide because there is a greater amount of carbon dioxide that needs to be captured.

The consumption of reactants and generation of products can be determined from the basis of CO₂ captured and the molecular weights of each input and each output for each example.

TABLE 10 Molecular Masses of Inputs and Outputs (all embodiments). Compound Molecular Weight CaSiO₃ 116.16 MgSiO₃ 99.69 Diopside* 215.85 CaCO₃ 100.09 MgCO₃ 84.31 Dolomite* 184.40 SiO₂ 60.08 CO₂ 44.01 *Number of moles must be divided by 2 to measure comparable CO₂ absorption with the other processes, For Examples 10-13:

The CaSiO₃ consumption is: 6,845,184 tons per year*(116.16/44.01)=18,066,577 tons per year.

The CaCO₃ production is: 6,845,184 tons per year*(100.09/44.01)=15,559,282 tons per year.

The SiO₂ production is: 6,845,184 tons per year*(60.08/44.01)=9,344,884 tons per year

The same type of calculations may be done for the remaining examples. This following table contains the inputs and outputs for examples 10 through 21. Basis: 6,845,184 tons CO₂ absorbed per year.

TABLE 11 Mass Flows of Inputs and Outputs for Examples 10-21. All measurements are in tons per year (TPY) Examples 10-13 14-17 18-21 CO₂ absorbed 6,845,184 6,845,184 6,845,184 INPUTS Flue Gas for CO₂ Capture 136,903,680 136,903,680 136,903,680 10% CO₂ 13,690,368 13,690,368 13,690,368 CaSiO₃ 18,066,577 MgSiO₃ 15,613,410 Diopside 16,839,993 OUTPUTS SiO₂ 9,344,884 9,344,884 9,344,884 CaCO₃ 15,559,282 MgCO₃ 13,111,817 Dolomite 14,319,845

Running the Aspen models generated the following results for the heat duty for each step of the decomposition reaction, dehydration and decomposition. The results for each example are summarized in the table below.

TABLE 12 Power (Rate of Energy for each process at the particular basis of CO₂ absorption). Process HEAT BALANCE CaSiO₃—Mg(OH)Cl CaSiO₃—MgO MgSiO₃—Mg(OH)Cl MgSiO₃—MgO Diop.-Mg(OH)Cl Diop.-MgO Examples 10, 11 12, 13 14, 15 16, 17 18, 19 20, 21 Dehydration Chamber (MW) 2670 1087 n/a n/a 2614 1306 HEX TO DI (210° C.) Source HCl reacting with silicate Decomposition Chamber (MW) 1033 1297 1226 1264 1231 1374 Decomposition Temp. ° C. 210 450 210 450 210 450 Source Flue Gas Total heat used for D&D* (MW) 3703 2384 1226 1264 3854 2680 *D&D equals dehydration and decomposition

TABLE 13 Percentage CO₂ captured as a function of flue gas temperature and CO₂ concentration. Examples 10 through 13. Process CaSiO₃—Mg(OH)Cl CaSiO₃—MgO CaSiO₃—Mg(OH)Cl CaSiO₃—MgO Flue Gas Source/Temp. Coal Coal Coal Coal Coal Coal Nat. gas Nat. gas 320° C. 360° C. 400° C. 440° C. 550° C. 550° C. 600° C. 600° C. Example # 10 10 10 10 10 12 11 13 % CO₂  7% 33% 45% 57% 70% 105%  83% 121%  96% 10% 24% 32% 41% 50% 75% 60% 87% 69% 14% 17% 23% 29% 36% 54% 43% 62% 50% 18% 13% 18% 23% 28% 42% 33% 48% 39%

A value of over 100% means that excess heat is available to produce more Mg(OH)Cl or MgO. FIG. 24 illustrates the percent CO₂ captured for varying CO₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and also whether the process relied on full or partial decomposition for examples 10 through 13 of the CaSiO₃—Mg(OH)Cl and CaSiO₃—MgO processes.

TABLE 14 Percentage CO₂ captured as a function of flue gas temperature and CO₂ concentration. Examples 14 through 17. Process MgSiO₃—Mg(OH)Cl MgSiO₃—MgO MgSiO₃—Mg(OH)Cl MgSiO₃—MgO Flue Gas Source/Temp. Coal Coal Coal Coal Coal Coal Ngas Ngas 320° C. 360° C. 400° C. 440° C. 550° C. 550° C. 600° C. 600° C. Example # 14 14 14 14 14 16 15 17 % CO₂  7% 24% 34% 45% 55% 84% 86% 93% 96% 10% 17% 25% 32% 40% 61% 62% 67% 69% 14% 12% 18% 23% 28% 43% 44% 48% 49% 18% 10% 14% 18% 22% 34% 34% 37% 38%

FIG. 25 illustrates the percent CO₂ captured for varying CO₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and also whether the process relied on full or partial decomposition for examples 14 through 17 of the MgSiO₃—Mg(OH)Cl and MgSiO₃—MgO processes.

TABLE 15 Percentage CO₂ captured as a function of flue gas temperature and CO₂ concentration. Examples 18 through 21. Process Diopside-Mg(OH)Cl Diop-MgO Diop-Mg(OH)Cl Diop-MgO Flue Gas Source/Temp. Coal Coal Coal Coal Coal Coal Ngas Ngas 320° C. 360° C. 400° C. 440° C. 550° C. 550° C. 600° C. 600° C. Example # 18 18 18 18 18 20 19 21 % CO₂  7% 28% 38% 48% 59% 88% 79% 101%  91% 10% 20% 27% 35% 42% 63% 57% 73% 65% 14% 14% 19% 25% 30% 45% 40% 52% 47% 18% 11% 15% 19% 23% 35% 31% 41% 36% *Note Diop equals Diopside

FIG. 26 illustrates the percent CO₂ captured for varying CO₂ flue gas concentrations, varying temperatures, whether the flue gas was originated from coal or natural gas, and also whether the process relied on full or partial decomposition for examples 18 through 21 of the Diopside-Mg(OH)Cl and Diopside-MgO processes.

TABLE 16a Mass and Energy Accounting for Examples 10 and 11 Simulation. Process Stream Names 1 2 CaCl₂ CaCl₂—Si CaCO₃ CaSiO₃ FLUE GAS H₂O HCl HCl Vapor PH Temperature 112.6 95 149.9 150 95 25 100 25 200 250 ° C. Pressure 14.696 15 100 14.696 14.7 14.696 15.78 14.7 14.696 14.696 psia Mass VFrac 0 0.793 0 0 0 0 1 0 1 1 Mass SFrac 1 0.207 0 0.163 1 1 0 0 0 0 Mass Flow 5.73E+07 3.96E+07 4.36E+07 5.21E+07 1.41E+07  164E+07 6.21E+07 1.80E+07 3.57E+07 3.57E+07 tonne/year Volume Flow 11216.8 2.2E+07 17031.4 18643.542 2616.633 2126.004 3.11E+07 502184.16 3.30E+07 3.65E+07 gal/min Enthalpy −22099.5 −3288.21 −17541.7 −21585.353 −5368.73 −7309.817 −2926.806 −9056.765 −11331.898 −11240.08 MW Density 160.371 0.059 80.305 87.619 169.173 241.725 0.063 1.125 0.034 0.031 lb/cuft H₂O 0 1.80E+07 2.79E+07 2.79E+07 0 0 3.10E+06 1.80E+07 2.54E+07 2.54E+07 HCl 0 0 0.004 0.004 0 0 0 0 1.03E+07 1.03E+07 CO₂ 0 0 0 0 0 0 6.21E+06 0 0 0 O₂ 0 0 0 0 0 0 6.21E+06 0 0 0 N₂ 0 0 0 0 0 0 4.65E+07 0 0 0 CaCO₃ 0 0 0 0 1.41E+07 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 0 0 MgCl₂*6W 5.73E+07 0 0 0 0 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 0 0 0 Mg(OH)₂ 0 8.22E+06 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 0 0 SO₂ 0 0 0 0 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 0 0 0 0 NO 0 0 0 0 0 0 0 0 0 0 Mg²⁺ 0 3.43E+06 0 0 0 0 0 0 0 0 Ca²⁺ 0 0 5.65E+06 5.65E+06 0 0 0 0 0 0 Cl⁻ 0 1.00E+07 1.00E+07 1.00E+07 0 0 0 0 0 0 CO3²⁻ 0 0 0 0 0 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 0 0 0 0 0 OH⁻ 0 0 0 0 0 0 0 0 0 0 CaSiO₃ 0 0 0 .007 0 1.64E+07 0 0 0 0 SiO₂ 0 0 0 8.47E+06 0 0 0 0 0 0

TABLE 16b Mass and Energy Accounting for Examples 10 and 11 Simulation. Process Stream Names MgCl₂—2W MgCl₂—6W RECYCLE1 RX2-VENT SiO₂ SLURRY SOLIDS-1 SOLIDS-2 PH 9.453 9.453 Temperature C 215 80 95 95 149.9 95 250 115 Pressure 14.696 14.696 14.7 14.7 100 14.7 14.696 14.696 psia Mass VFrac .502 0 0 1 0 0 0 .165 Mass SFrac .498 1 0 0 1 .152 1 .207 Mass Flow 5.73E+07 5.73E+07 7.84E+07 5.27E+07 8.47E+06 9.26E+07 2.16E+07 3.96E+07 tonne/year Volume 3.03E+07 11216.796 33789.492  282E+07 1607.826 32401.78 3828.933 6.33E+06 Flow gal/min Enthalpy −1877.989 −22191.287 −32705.27 120.09 0 −38074.2 −7057.97 −4070.06 MW Density .059 160.371 72.846 0.059 165.327 89.628 177.393 0.197 lb/cuft H₂O 2.54E+07 0 5.16E+07 0 0 5.16E+07 0 1.80E+07 HCl 3.40E+06 0 0 0 0 0 0 0 CO₂ 0 0 0.074 25.781 0 0.074 0 0 O₂ 0 0 2510.379 6.20E+06 0 2510.379 0 0 N₂ 0 0 8109.244 4.65E+07 0 8109.245 0 0 CaCO₃ 0 0 0 0 0 1.41E+07 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 2.14E+07 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 5.73E+07 0 0 0 0 0 0 Mg(OH)Cl 7.15E+06 0 0 0 0 0 2.16E+07 0 Mg(OH)₂ 0 0 0 0 0 0 0 8.22E+06 MgO 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 3324.433 0 0 3324.433 0 0 SO₂ 0 0 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 0 0 NO 0 0 0 0 0 0 0 0 Mg²⁺ 0 0 6.85E+06 0 0 6.85E+06 0 3.43E+06 Ca²⁺ 0 0 1644.031 0 0 1644.031 0 0 Cl⁻ 0 0 2.00E+07 0 0 2.00E+07 0 1.00E+07 CO₃ 0 0 61.424 0 0 61.424 0 0 HCO₃ 0 0 27.297 0 0 27.297 0 0 OH⁻ 0 0 690.278 0 0 690.278 0 0 CaSiO₃ 0 0 0 0 0.007 0 0 0 SiO₂ 0 0 0 0 8.47E+06 0 0 0

TABLE 17a Mass and Energy Accounting for Examples 12 and 13 Simulation. Process Stream Names FLUE HCl 1 2 CaCl₂ CaCl₂—Si CaCO₃ CaSiO₃ GAS H₂O HCl Vapor PH Temperature 271 255.5 149.8 150 95 25 100 25 200 450 ° C. Pressure psia 14.696 15 100 14.696 14.7 14.696 15.78 14.7 14.696 14.696 Mass VFrac 0 0 0 0 0 0 1 0 1 1 Mass SFrac 1 1 0 0.215 1 1 0 0 0 0 Mass Flow 2.87E+07 2.37E+07 3.09E+07 3.94E+07 1.41E+07 1.64E+07 6.21E+07 1.80E+07 2.30E+07 2.30E+07 tonne/year Volume Flow 5608.398 10220.835 10147.12 11758.176 2616.827 2126.004 3.11E+07 502184.16 1.93E+07 2.94E+07 gal/min Enthalpy MW −10826.6 −11660.74 −11347.9 −15391.633 −5369.12 −7309.817 −2926.806 −9056.765 −6056.076 −5786.994 Density lb/cuft 160.371 72.704 95.515 105.035 169.173 241.725 0.063 1.125 0.037 0.024 H₂O 0 1.55E+07 1.52E+07 1.52E+07 0 0 3.10E+06 1.80E+07 1.27E+07 1.27E+07 HCl 0 0 0.015 0.015 0 0 0 0 1.03E+07 1.03e+07 CO₂ 0 0 0 0 0 0 6.21E+06 0 0 0 O₂ 0 0 0 0 0 0 6.21E+06 0 0 0 N₂ 0 0 0 0 0 0 4.65E+07 0 0 0 CaCO₃ 0 0 0 0 1.41E+07 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 0 0 MgCl₂*6W 2.87E+07 0 0 0 0 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 0 0 0 Mg(OH)₂ 0 8.22E+06 0 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 0 0 0 SO₂ 0 0 0 0 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 0 0 0 0 NO 0 0 0 0 0 0 0 0 0 0 Mg²⁺ 0 0 0 0 0 0 0 0 0 0 Ca²⁺ 0 0 5.65E+06 5.65E+06 0 0 0 0 0 0 Cl⁻ 0 0 1.00E+07 1.00E+07 0 0 0 0 0 0 CO₃ ²⁻ 0 0 0 0 0 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 0 0 0 0 0 OH⁻ 0 0 0 0 0 0 0 0 0 0 CaSiO₃ 0 0 0 0.023 1.64E+07 0 0 0 0 0 SiO₂ 0 0 0 8.47E+06 0 0 0 0 0 0

TABLE 17b Mass and Energy Accounting for Examples 12 and 13 Simulation. Process Stream Names RX2- MgCl₂-2W MgCl₂-6W RECYCLE1 VENT SiO₂ SLURRY SOLIDS-1 SOLIDS-2 PH 9.304 9.304 Temperature 215 80 95 95 149.8 95 450 115 ° C. Pressure psia 14.696 14.696 14.7 14.7 100 14.7 14.696 14.696 Mass VFrac 0.502 0 0 1 0 0 0 0 Mass SFrac 0.498 1 0 0 1 0.221 1 1 Mass Flow 2.87E+07 2.87E+07 4.98E+07 5.27E+07 8.47E+06 6.39E+07 5.68E+06 2.37E+07 tonne/year Volume Flow 1.51E+07 5608.398 25330.305 2.82E+07 1607.826 22988.79 797.11 10220.84 gal/min Enthalpy MW −9388.949 −11095.644 −21589.89 120.08 0 −26959.3 −2603.98 −11955.9 Density lb/cuft 0.059 160.371 61.662 0.059 165.327 87.199 223.695 72.704 H₂O  127E+07 0 3.63E+07 0 0 3.63E+07 0 1.55E+07 HCl 1.70E+07 0 0 0 0 0 0 0 CO₂ 0 0 0.145 79.255 0 0.145 0 0 O₂ 0 0 1919.222 6.20E+06 0 1919.222 0 0 N₂ 0 0 6199.3 4.65E+07 0 6199.301 0 0 CaCO₃ 0 0 0 0 0 1.41E+07 0 0 MgCl₂ 0 0 0 0 0 0 0 0 MgCl₂*W 1.07E+07 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 0 MgCl₂*6W 0 2.87E+07 0 0 0 0 0 0 Mg(OH)Cl 3.58E+06 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 8.22E+06 MgO 0 0 0 0 0 0 5.68E+06 0 MgHCO₃ ⁺ 0 0 2208.676 0 0 2208.676 0 0 SO₂ 0 0 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 0 0 NO 0 0 0 0 0 0 0 0 Mg²⁺ 0 0 3.43E+06 0 0 3.43E+06 0 0 Ca²⁺ 0 0 1225.309 0 0 1225.309 0 0 Cl⁻ 0 0 1.00E+07 0 0 1.00E+07 0 0 CO₃ ²⁻ 0 0 110.963 0 0 110.963 0 0 HCO₃ ⁻ 0 0 63.12 0 0 63.12 0 0 OH⁻ 0 0 519.231 0 0 519.231 0 0 CaSiO₃ 0 0 0 0 0.023 0 0 0 SiO₂ 0 0 0 0 8.47E+06 0 0 0

TABLE 18a Mass and Energy Accounting for Examples 14 and 15 Simulation. Process Stream Names FLUE HCl GAS H₂O H₂O Vapor MgCl₂--2 MgCl₂-2w MgCl₂—Si PH Temperature 100 25 26 250 200.7 200 200 ° C. Pressure psia 15.78 1 14.696 14.696 15 14.696 14.696 Mass VFrac 1 0 0.798 1 0.238 0 0.169 Mass SFrac 0 0 0.186 0 0 1 0.289 Mass Flow 1.37E+08 1.00E+07 1.58E+08 1.69E+07 2.31E+07 4.08E+07 3.26E+07 tons/year Volume Flow 62.21E+07  4569.619 4.91E+07 1.22E+07 5.22E+06 3828.933 5.33E+06 gal/min Enthalpy MW −5853.92 −4563.814 −13984.7 −2861.732 0 −11194.13 −10932.15 Density lb/cuft 0.063 62.249 0.091 0.04 0.126 303.28 0.174 H₂O 6.85E+06 1.00e+07 5.19E+06 5.60E+06 8.37E+06 0 8.37E+06 HCl 0 0 0 1.13E+07 126399.9 0 126399.87 CO₂ 1.37E+07 0 6.85E+06 0 0 0 0 O₂ 1.37E+07 0 1.37E+07 0 0 0 0 N₂ 1.03E+08 0 1.03E+08 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 4.08E+07 0 MgCl₂*4W 0 0 1.09E+07 0 0 0 0 MgCl₂*6W 0 0 1.83E+07 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0.001 0 0 0 0 SO₂ 0 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 0 NO 0 0 0 0 0 0 0 Mg²⁺ 0 0 0 0 3.74E+06 0 3.74E+06 Cl⁻ 0 0 0 0 1.09E+07 0 1.09E+07 CO₃ ²⁻ 0 0 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 0 0 OH⁻ 0 0 0 0 0 0 0 SiO₂ 0 0 0 0 0 0 9.24E+06 MgSiO₃ 0 0 0 0 0 0 174011.19

TABLE 18b Mass and Energy Accounting for Examples 14 and 15 Simulation. Process Stream Names RX2- MgCO₃ MgSiO₃ VENT SiO₂ SLURRY SOLIDS-1 SOLIDS-2 PH .0864 6.24 Temperature 26 25 200.7 60 250 95 ° C. Pressure psia 14.696 14.696 15 44.088 14.696 44.088 Mass VFrac 0 0 0 0 0 0 Mass SFrac 1 1 1 0.248 1 0.268 Mass Flow 1.31E+07 1.56E+07 0 9.41E+06 1.71E+08 2.39E+07 3.39E+07 tons/year Volume Flow 1985.546 2126.004 1613.601 178707.499 3828.933 8016.874 gal/min Enthalpy MW 0 −6925.208 0 0 −18961.843 −7057.974 −12123.17 Density lb/cuft 187.864 208.902 165.967 27.184 177.393 120.206 H₂O 0 0 0 5.19E+06 0 1.00E+07 HCl 0 0 0 0 0 0 CO₂ 0 0 0 6.85E+06 0 0 O₂ 0 0 0 1.37E+07 0 0 N₂ 0 0 0 1.03E+08 0 0 MgCO₃ 1.31E+07 0 0 1.31E+07 0 0 MgCl₂ 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 MgCl₂*4W 0 0 0 1.09E+07 0 0 MgCl₂*6W 0 0 0 1.83E+07 0 0 Mg(OH)Cl 0 0 0 0 2.39E+07 0 Mg(OH)₂ 0 0 0 0 0 9.07E+06 MgO 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0.001 0 0 SO₂ 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 NO 0 0 0 0 0 0 Mg²⁺ 0 0 0 0 0 3.78E+06 Cl⁻ 0 0 0 0 0 1.10E+07 CO3²⁻ 0 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 0 OH⁻ 0 0 0 0 0 0.029 SiO₂ 0 0 9.24E+06 0 0 0 MgSiO₃ 0 1.56E+07 174011.19 0 0 0

TABLE 19a Mass and Energy Accounting for Examples 16 and 17 Simulation. Process Stream Names FLUE HCl GAS H₂O H₂O Vapor MgCl₂--2 MgCl₂-2w MgCl₂—Si PH 6.583 Temperature 100 25 59.6 450 200 200 200 ° C. Pressure psia 15.78 1 14.696 14.696 15 14.696 14.696 Mass VFrac 1 0 0.004 1 0 0 0 Mass SFrac 0 0 0 0 1 1 1 Mass Flow 1.37E+08 1.00E+07 1.70E+07 1.41E+07 2.04E+07 2.04E+07 2.98e+07 tons/year Volume Flow 6.21E+07 4569.619 40446.86 1.26E+07 1914.466 1914.466 3522.292 gal/min Enthalpy MW −5853.92 4563.814 −7633.28 −1728.6 0 −5597.066 −9628.072 Density lb/cuft 0.063 62.249 11.94 0.032 303.28 303.28 240.308 H₂O 685.E+06 1.00E+07 1.68E+07 2.80E+06 0 0 0 HCl 0 0 0 1.13E+07 0 0 0 CO₂ 1.37E+07 0 56280.04 0 0 0 0 O₂ 1.37E+07 0 18848.97 0 0 0 0 N₂ 1.03E+08 0 56346.51 0 0 0 0 MgCO₃ 0 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 2.04E+07 2.04E+07 2.04E+07 MgCl₂*4W 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 77.467 0 0 0 0 SO₂ 0 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 0 NO 0 0 0 0 0 0 0 Mg²⁺ 0 0 744.857 0 0 0 0 Cl⁻ 0 0 0 0 0 0 0 CO₃ ²⁻ 0 0 1.19 0 0 0 0 HCO₃ ⁻ 0 0 3259.779 0 0 0 0 OH⁻ 0 0 0.109 0 0 0 0 SiO₂ 0 0 0 0 0 0 9.34E+06 MgSiO₃ 0 0 0 0 0 0 0

TABLE 19b Mass and Energy Accounting for Examples 16 and 17 Simulation. Process Stream Names RX2- MgCO₃ MgSiO₃ VENT SiO₂ SLURRY SOLIDS-1 SOLIDS-2 PH 6.583 8.537 Temperature 59.6 25 60 200 60 450 95 ° C. Pressure psia 14.696 14.696 44.088 15 44.088 14.696 44.088 Mass VFrac 0 0 1 0 0 0 0 Mass SFrac 1 1 0 1 0.436 1 0.558 Mass Flow 1.31E+07 1.56E+07 1.23E+08 9.34E+06 3.01E+07 6.27E+06 1.63E+07 tons/year Volume Flow 1983.661 2126.004 1.76E+07 1607.826 9945.342 797.11 5155.55 gal/min Enthalpy MW 0 −6925.208 −1613.054 0 −12593.788 −2603.979 −7331.893 Density lb/cuft 187.864 208.902 0.199 165.327 86.031 223.695 89.76 H₂O 0 0 0 0 1.68E+07 0 7.20E+06 HCl 0 0 0 0 0 0 0 CO₂ 0 0 6.78E+06 0 56280.036 0 0 O₂ 0 0 1.37E+07 0 18848.966 0 0 N₂ 0 0 1.03E+08 0 56346.51 0 0 MgCO₃ 1.31E+07 0 0 0 1.31E+07 0 0 MgCl₂ 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 9.07E+06 MgO 0 0 0 0 0 6.27E+06 0 MgHCO₃ ⁺ 0 0 343.415 0 77.467 0 0 SO₂ 0 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 0 NO 0 0 0 0 0 0 0 Mg²⁺ 0 0 2722.849 0 744.857 0 14.282 Cl⁻ 0 0 0 0 0 0 0 CO₃ ²⁻ 0 0 4.344 0 1.19 0 0 HCO₃ ⁻ 0 0 14439.982 0 3259.779 0 0 OH⁻ 0 0 0.481 0 0.109 0 19.989 SiO₂ 0 0 0 9.34E+06 0 0 0 MgSiO₃ 0 1.56E+07 0 0 0 0 0

TABLE 20a Mass and Energy Accounting for Examples 18 and 19 Simulation. Process Stream Names FLUE HCl- HCl 5 CaCl₂-2W GAS H₂O HCl VENT VAP2 PH Temperature 200 160 100 25 250 100 349.1 ° C. Pressure psia 14.696 14.696 15.78 1 14.696 14.696 14.696 Mass VFrac 0.378 0.473 1 0 1 1 1 Mass SFrac 0.622 0 0 0 0 0 0 Mass Flow 6.32E+07 2.40E+07 1.37E+08 1.00E+07 3.94E+07 0.001  197E+07 tons/year Volume Flow 2.29E+07 1.02E+07 6.21E+07 4569.619 3.64E+07 0.001 1.82E+07 gal/min Enthalpy MW −19530.7 −8042.026 −5853.92 −4563.814 −11241.7 0 −5620.856 Density lb/cuft 0.079 0.067 0.063 62.249 0.031 0.075 0.031 H₂O 2.29E+07 1.54E+07 6.85E+06 1.00E+07 2.08E+07 0 1.40E+07 HCl 983310.7 0 0 0 1.13E+07 0.001 5.67E+06 CO₂ 0 0 1.37E+07 0 0 0 0 O₂ 0 0 1.37E+07 0 0 0 0 N₂ 0 0 1.03E+08 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 MgCl₂*2W 3.73E+07 0 0 0 0 0 0 MgCl₂MW 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 0 0 Mg(OH)Cl 2.07E+06 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 SO₂ 0 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 0 NO 0 0 0 0 0 0 0 Mg²⁺ 0 2494.617 0 0 0 0 0 Ca²⁺ 0 3.11E+06 0 0 0 0 0 Cl⁻ 0 5.51E+06 0 0 0 0 0 CO₃ ²⁻ 0 0 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 0 0 OH⁻ 0 0 0 0 0 0 0 CaSiO₃ 0 0 0 0 0 0 0 SiO₂ 0 0 0 0 0 0 0 MgSiO₃ 0 0 0 0 0 0 0 DIOPSIDE 0 0 0 0 0 0 0 DOLOMITE 0 0 0 0 0 0 0 Process Stream Names HCl HCl Vapor VENT2 MELT1 MELT2 MELT3 PH Temperature 349.1 160 160 160 100 ° C. Pressure psia 14.696 14.696 14.696 14.696 14.696 Mass VFrac 1 1 0.311 0 0 Mass SFrac 0 0 0.342 1 0.291 Mass Flow 1.97E+07 26.688 3.65E+07 1.25E+07 3.22E+07 tons/year Volume Flow 1.82E+07 11.834 1.02E+07 1866.916 9636.543 gal/min Enthalpy MW −5620.856 −0.002 −13498.19 −5456.154 −12759.563 Density lb/cuft 0.031 0.064 0.102 190.163 94.933 H₂O 1.40E+07 0 1.54E+07 0 1.54E+07 HCl 5.67E+06 26.688 26.688 0 0.001 CO₂ 0 0 0 0 0 O₂ 0 0 0 0 0 N₂ 0 0 0 0 0 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂MW 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 MgO 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 SO₂ 0 0 0 0 0 NO₂ 0 0 0 0 0 NO 0 0 0 0 0 Mg²⁺ 0 0 2494.617 0 1.89E+06 Ca²⁺ 0 0 3.11E+06 0 4128.267 Cl⁻ 0 0 5.51E+06 0 5.51E+06 CO₃ ²⁻ 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 OH⁻ 0 0 0 0 0 CaSiO₃ 0 0 11965.659 11965.659 0 SiO₂ 0 0 4.67E+06 4.67E+06 9.34E+06 MgSiO₃ 0 0 7.80E+06 7.80E+06 36.743 DIOPSIDE 0 0 0 0 0 DOLOMITE 0 0 0 0 0

TABLE 20b Mass and Energy Accounting for Examples 18 and 19 Simulation. Process Stream Names MgCaSiO₃ MgCl₂—H MgCl₂—H RECYCLE RECYCLE- SiO₂ PH Temperature 25 100 100 95 95 100 ° C. Pressure psia 14.696 14.696 14.696 14.696 14.696 14.696 Mass VFrac 0 0 0 0 0 0 Mass SFrac 1 0 1 0.828 1 1 Mass Flow  168E+07 2.28E+07 4.74E+07 5.73E+07 1.58E+07 9.34E+06 tons/year Volume Flow 1063.002 8028.716 8412.597 13075.55 2804.199 1607.827 gal/min Enthalpy MW −7167.458 0 −16601.2 −21023.6 −5537.26 0 Density lb/cuft 450.627 80.836 160.371 124.605 160.371 165.327 H₂O 0 1.54E+07 0 9.84E+07 0 0 HCl 0 0 0 0 0 0 CO₂ 0 0 0 0 0 0 O₂ 0 0 0 0 0 0 N₂ 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 MgCl₂*6W 0 0 4.74E+07 4.74E+07 1.58E+07 0 Mg(OH)Cl 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 12011.06 0 0 MgO 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 11.135 0 0 SO₂ 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 NO 0 0 0 0 0 0 Mg²⁺ 0 1.89E+06 0 0 0 0 Ca²⁺ 0 4128.267 0 0 0 0 Cl⁻ 0 5.51E+06 0 4.627 0 0 CO₃ ²⁻ 0 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 0 OH⁻ 0 0 0 0 0 0 CaSiO₃ 0 0 0 0 0 0 SiO₂ 0 0 0 0 0 9.34E+06 MgSiO₃ 0 0 0 0 0 36.743 DIOPSIDE 1.68E+07 0 0 0 0 0 DOLOMITE 0 0 0 0 0 0 Process Stream Names SLURRY SOLIDS SOLIDS-1 SOLIDS-2 VENT PH 5.163 6.252 Temperature 95 95 250 95 95 ° C. Pressure psia 14.696 14.696 14.696 14.696 14.696 Mass VFrac 0 0 0 0 1 Mass SFrac 0.317 1 1 0.268 0 Mass Flow 1.95E+08 1.43E+07 2.39E+07 3.39E+07 1.23E+08 tons/year Volume Flow 185622 2276.765 3828.933 8017.333 5.85E+07 gal/min Enthalpy MW −27714.4 0 −7057.97 −12113.4 −1510.76 Density lb/cuft 29.855 178.921 177.393 120.2 0.06 H₂O 9.84E+06 0 0 1.00E+07 0 HCl 0 0 0 0 0 CO₂ 6.85E+06 0 0 0 6.85E+06 O₂ 1.37E+07 0 0 0 1.37E+07 N₂ 1.03E+08 0 0 0 1.03E+08 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 MgCl₂*6W 4.74E+07 0 0 0 0 Mg(OH)Cl 0 0 2.39E+07 0 0 Mg(OH)₂ 12011.06 0 0 9.07E+06 0 MgO 0 0 0 0 0 MgHCO₃ ⁺ 11.135 0 0 0 0 SO₂ 0 0 0 0 0 NO₂ 0 0 0 0 0 NO 0 0 0 0 0 Mg²⁺ 0 0 0 3.78E+06 0 Ca²⁺ 0 0 0 0 0 Cl⁻ 4.627 0 0 1.10E+07 0 CO₃ ²⁻ 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 OH⁻ 0 0 0 0.03 0 CaSiO₃ 0 0 0 0 0 SiO₂ 0 0 0 0 0 MgSiO₃ 0 0 0 0 0 DIOPSIDE 0 0 0 0 0 DOLOMITE 1.43E+07 1.43E+07 0 0 0

TABLE 21a Mass and Energy Accounting for Examples 20 and 21 Simulation. Process Stream Names FLUE HCl- HCl 5 CaCl₂-2W GAS H₂O HCl VENT VAP2 PH Temperature 200 160 100 25 450 100 449.5 ° C. Pressure psia 14.696 14.696 15.78 1 14.696 14.696 14.696 Mass VFrac 0.378 0.256 1 0 1 1 1 Mass SFrac 0.622 0 0 0 0 0 0 Mass Flow 3.16E+07 1.70E+07 1.37E+08 1.00E+07 2.54E+07 0.006 1.27E+07 tons/year Volume Flow 1.14E+07 3.91E+06 6.21E+07 4569.619 2.94E+07 0.002 1.47E+07 gal/min Enthalpy MW −9765.36 −5388.055 −5853.92 −4563.814 −5787.5 0 −2893.751 Density lb/cuft 0.079 0.124 0.063 62.249 0.025 0.075 0.025 H₂O 1.15E+07 8.41E+06 6.85E+06 1.00E+07 1.40e+07 0 7.00E+06 HCl 491655.4 0 0 0 1.13E+07 0.006 5.67E+06 CO₂ 0 0 1.37E+07 0 0 0 0 O₂ 0 0 1.37E+07 0 0 0 0 N₂ 0 0 1.03E+08 0 0 0 0 MgCl₂ 0 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 0 MgCl₂*2W 1.86E+07 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 0 0 Mg(OH)Cl 1.04E+06 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 0 0 MgO 0 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 0 0 SO₂ 0 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 0 NO 0 0 0 0 0 0 0 Mg²⁺ 0 2494.624 0 0 0 0 0 Ca²⁺ 0 3.11E+06 0 0 0 0 0 Cl⁻ 0 5.51E+06 0 0 0 0 0 CO₃ ²⁻ 0 0 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 0 0 OH⁻ 0 0 0 0 0 0 0 CaSiO₃ 0 0 0 0 0 0 0 SiO₂ 0 0 0 0 0 0 0 MgSiO₃ 0 0 0 0 0 0 0 DIOPSIDE 0 0 0 0 0 0 0 DOLOMITE 0 0 0 0 0 0 0 Process Stream Names HCl HCl Vapor VENT2 MELT1 MELT2 MELT3 PH Temperature 449.5 160 160 160 100 ° C. Pressure psia 14.696 14.696 14.696 14.696 14.696 Mass VFrac 1 1 0.148 0 0 Mass SFrac 0 0 0.423 1 0.371 Mass Flow 1.27E+07 10.275 2.95E+07 1.25E+07 2.52E+07 tons/year Volume Flow 1.47E+07 4.556 3.91E+06 1866.915 6342.437 gal/min Enthalpy MW −2893.751 −.0001 −10844.21 −5456.149 −9602.42 Density lb/cuft 0.025 0.064 0.215 190.163 112.823 H₂O 7.00E+06 0 8.41E+06 0 8.41.E+06  HCl 5.67E+06 10.275 10.275 0 0.006 CO₂ 0 0 0 0 0 O₂ 0 0 0 0 0 N₂ 0 0 0 0 0 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 MgCl₂*6W 0 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 Mg(OH)₂ 0 0 0 0 0 MgO 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 0 0 SO₂ 0 0 0 0 0 NO₂ 0 0 0 0 0 NO 0 0 0 0 0 Mg²⁺ 0 0 2494.624 0 1.89E+06 Ca²⁺ 0 0 3.11E+06 0 4119.258 Cl⁻ 0 0 5.51E+06 0 5.51E+06 CO₃ ²⁻ 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0 0 OH⁻ 0 0 0 0 0 CaSiO₃ 0 0 11939.547 11939.547 0 SiO₂ 0 0 4.67E+06 4.67E+06 9.34E+06 MgSiO₃ 0 0 7.80E+06 7.80E+06 14.153 DIOPSIDE 0 0 0 0 0 DOLOMITE 0 0 0 0 0

TABLE 21b Mass and Energy Accounting for Examples 20 and 21 Simulation. Process Stream Names MgCaSiO3 MgCl₂—H MgCl₂—H RECYCLE RECYCLE- SiO₂ PH −0.879 Temperature 25 100 100 95 95 100 ° C. Pressure psia 14.696 14.696 14.696 14.696 14.696 14.696 Mass VFrac 0 0 0 0 0 0 Mass SFrac 1 0 1 0 0.484 1 Mass Flow 1.68E+07 1.58E+07 1.58E+07 3.27E+07 1.58E+07 9.34E+06 tons/year Volume Flow 1063.002 4734.61 2804.199 10786.59 2804.199 1607.826 gal/min Enthalpy MW −7167.458 0 −5533.74 −13087 −5537.26 0 Density lb/cuft 450.627 94.994 160.371 86.167 160.371 165.327 H₂O 0 8.41E+06 0 1.68E+07 0 0 HCl 0 0 0 0 0 0 CO₂ 0 0 0 0 0 0 O₂ 0 0 0 0 0 0 N₂ 0 0 0 0 0 0 MgCl₂ 0 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 0 MgCl₂*6W 0 0 1.58E+07 1.58E+07 1.58E+07 0 Mg(OH)Cl 0 0 0 0 0 0 Mg(OH)₂ 0 0 0 11678.01 0 0 MgO 0 0 0 0 0 0 MgHCO₃ ⁺ 0 0 0 908.901 0 0 SO₂ 0 0 0 0 0 0 NO₂ 0 0 0 0 0 0 NO 0 0 0 0 0 0 Mg²⁺ 0 1.89E+06 0 0 0 0 Ca²⁺ 0 4119.258 0 0 0 0 Cl⁻ 0 5.51E+06 0 377.667 0 0 CO₃ ²⁻ 0 0 0 0 0 0 HCO₃ ⁻ 0 0 0 0.006 0 0 OH⁻ 0 0 0 0 0 0 CaSiO₃ 0 0 0 0 0 0 SiO₂ 0 0 0 0 0 9.34E+06 MgSiO₃ 0 0 0 0 0 14.153 DIOPSIDE 1.68E+07 0 0 0 0 0 DOLOMITE 0 0 0 0 0 0 Process Stream Names SLURRY SOLIDS SOLIDS-1 SOLIDS-2 VENT PH 5.271 8.545 Temperature 95 95 450 95 95 ° C. Pressure psia 14.696 14.696 14.696 14.696 14.696 Mass VFrac 0 0 0 0 1 Mass SFrac 1 0.177 1 1 0.558 Mass Flow 1.70E+08 1.43E+07 6.27E+06 1.63E+07 1.23E+08 tons/year Volume Flow 183332.5 2276.772 797.11 5155.892 5.85E+07 gal/min Enthalpy MW −19788.2 0 −2603.98 −7331.92 −1510.64 Density lb/cuft 26.409 178.921 223.695 89.754 0.06 H₂O 1.68E+07 0 0 7.20E+06 0 HCl 0 0 0 0 0 CO₂ 6.85E+06 0 0 0 6.85E+06 O₂ 1.37E+07 0 0 0 1.37E+07 N₂ 1.03E+08 0 0 0 1.03E+08 MgCl₂ 0 0 0 0 0 MgCl₂*W 0 0 0 0 0 MgCl₂*2W 0 0 0 0 0 MgCl₂*4W 0 0 0 0 0 MgCl₂*6W 1.58E+07 0 0 0 0 Mg(OH)Cl 0 0 0 0 0 Mg(OH)₂ 11678.01 0 0 9.07E+06 0 MgO 0 0 6.27E+06 0 0 MgHCO₃ ⁺ 908.901 0 0 0 0 SO₂ 0 0 0 0 0 NO₂ 0 0 0 0 0 NO 0 0 0 0 0 Mg²⁺ 0 0 0 14.555 0 Ca²⁺ 0 0 0 0 0 Cl⁻ 377.667 0 0 0 0 CO₃ ²⁻ 0 0 0 0 0 HCO₃ ⁻ 0.006 0 0 0 0 OH⁻ 0 0 0 0 0 CaSiO₃ 0 0 0 0 0 SiO₂ 0 0 0 0 0 MgSiO₃ 0 0 0 0 0 DIOPSIDE 0 0 0 0 0 DOLOMITE 1.43E+07 1.43E+07

Example 22 Decomposition of Other Salts

The thermal decomposition of other salts has been measured in lab. A summary of some test results are shown in the table below.

TABLE 22 Decomposition of other salts. Time Salt Temp.° C. (min.) Results Mg(NO₃)₂ 400 30 63% decomposition. Reaction is Mg(NO₃)₂ → MgO + 2NO₂ + ½ O₂ Mg(NO₃)₂ 400 45   64% decomposition. Mg(NO₃)₂ 400 90 100% decomposition Mg(NO₃)₂ 400 135 100% decomposition <25% decomposition Reaction is Ca(NO₃)₂ → CaO + Ca(NO₃)₂ 400 30 2NO₂ + ½ O₂ Ca(NO₃)₂ 600 50  61% decomposition Ca(NO₃)₂ 600 Overnight 100% decomposition LiCl 450 120  ~0% decomposition  

Example 22 Two, Three and Four-Chamber Decomposition Models

Table 23 (see below) is a comparison of the four configurations corresponding to FIGS. 31-34. Depicted are the number and description of the chambers, the heat consumed in MW (Megawatts), the percentage of heat from that particular source and the reduction of required external heat in kW-H/tonne of CO₂ because of available heat from other reactions in the process, namely the hydrochloric acid reaction with mineral silicates and the condensation of hydrochloric acid. In the FIG. 34 example, the hot flue gas from the open-cycle natural gas plant also qualifies.

Example 23 Output Mineral Compared with Input Minerals—Coal

In this case study involving flue gas from a coal-based power plant, Table 24 illustrates that the volume of mineral outputs (limestone and sand) are 83% of the volume of input minerals (coal and inosilicate). The results summarized in Table 24 are based on a 600 MWe coal plant; total 4.66 E6 tonne CO₂, includes CO₂ for process-required heat.

Example 24 Output Mineral Compared with Input Minerals—Natural Gas

In this case study summarized in Table 25 (below) involving flue gas from a natural gas-based power plant, the “rail-back volume” of minerals is 92% of the “rail-in volume” of minerals. The results summarized in Table 25 are (based on a 600 MWe CC natural gas plant; total 2.41 E6 tonne CO₂, which includes CO₂ for process-required heat.

TABLE 23 Two, Three and Four-Chamber Decomposition Results Chamber Description Pre-Heat Mineral Pre-heat Pre Heat Dissolution Reactor No. of Cold Flue from Silicate HCl Heat Example Chambers Gas Steam Reaction Recovery Decomposition FIG. 31 Cold Flue Gas Pre Heat MW of Heat 3 83.9 Not used  286  563  86.8 Percentage of Total Heat 8.2% Not used 28.0% 55.2% 8.5% Reduction kW-Hr/tonne −506.7    Not used −1727.4 −3400.5 Not a reduction FIG. 32 Cold Flue Gas and Steam Pre -Heat MW of Heat 4 83.9 8.7  286  563  82.2 Percentage of Total Heat 8.2% 0.8% 27.9% 55.0% 8.0% Reduction kW-Hr/tonne −506.7    −52.5    −1727.4 −3400.5 Not a reduction FIG. 33 Nat Gas Only MW of Heat 2 Not used Not used  279  586 129.3 Percentage of Total Heat Not used Not used 28% 59%  13% Reduction kW-Hr/tonne Not used Not used −1685.1 −3539.4 Not a reduction FIG. 34 Hot Flue Gas Only MW of Heat 2 Not used Not used  243  512 112.9 Percentage of Total Heat Not used Not used 28% 59%  13% Reduction kW-Hr/tonne Not used Not used −1467.7 −3092.4 −681.9  

TABLE 24 Coal Scenario-Volume of Mineral Outputs Compared with Volume of Mineral Inputs Metric Units English Units Bulk Mass Mass Volume Density (10⁶ Volume (10⁶ (10⁶ Parameter (Tonne/m³) Tonne/yr) (10⁶ m³/yr) Ton/yr) ft³/yr) Coal 0.8 1.57 1.97 1.73 69.5 CaSiO₃ 0.71 12.30 17.32 13.56 611.8 Coal + 681.25 CaSiO₃ CaCO₃ 0.9 10.60 11.78 11.68 415.9 SiO₂ 1.5 6.35 4.23 7.00 149.5 CaCO₃ + n/a 16.95 16.01 18.68 565.4 SiO₂ RATIO OF MINERAL VOLUME OUT/MINERAL 83.00% VOLUME IN =

TABLE 25 Natural Gas Scenario-Volume of Mineral Outputs Compared with Volume of Mineral Inputs Metric Units Bulk Mass English Units Density (10⁶ Volume Mass Volume Parameter (Tonne/m³) Tonne/yr) (10⁶ m³/yr) (10⁶ Ton/yr) (10⁶ ft³/yr) Coal 0.8 1.57 1.97 1.73 69.5 CaSiO₃ 0.71 12.30 17.32 13.56 611.8 Coal + 681.25 CaSiO₃ CaCO₃ 0.9 10.60 11.78 11.68 415.9 SiO₂ 1.5 6.35 4.23 7.00 149.5 CaCO₃ + n/a 16.95 16.01 18.68 565.4 SiO₂ RATIO OF MINERAL VOLUME OUT/MINERAL 83.00% VOLUME IN =

All of the methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of particular embodiments, it will be apparent to those of skill in the art that variations may be applied to the methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

REFERENCES

The following references, to the extent that they provide exemplary procedural or other details supplementary to those set forth herein, are specifically incorporated herein by reference.

-   U.S. Prov. Appln. 60/612,355 -   U.S. Prov. Appln. 60/642,698 -   U.S. Prov. Appln. 60/718,906 -   U.S. Prov. Appln. 60/973,948 -   U.S. Prov. Appln. 61/032,802 -   U.S. Prov. Appln. 61/033,298 -   U.S. Prov. Appln. 61/288,242 -   U.S. Prov. Appln. 61/362,607 -   U.S. patent application Ser. No. 11/233,509 -   U.S. patent application Ser. No. 12/235,482 -   U.S. Patent Pubn. 2006/0185985 -   U.S. Patent Pubn. 2009/0127127 -   U.S. Pat. No. 7,727,374 -   PCT Appln. PCT/US08/77122 -   Goldberg et al., Proceedings of First National Conference on Carbon     Sequestration, 14-17 May 2001, Washington, D.C., section 6c, United     States Department of Energy, National Energy Technology Laboratory.     available at:     http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/6cl.pdf. -   Proceedings of First National Conference on Carbon Sequestration,     14-17 May 2001, Washington, D.C. United States Department of Energy,     National Energy Technology Laboratory. CD-ROM USDOE/NETL-2001/1144;     also available at     http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/carbon_seq01.html. 

What is claimed is:
 1. A method of sequestering carbon dioxide produced by a source, comprising: (a) heating a magnesium chloride salt or a hydrate thereof and water in a first admixture to form (i) magnesium hydroxide, magnesium oxide and/or MgCl(OH) and (ii) hydrogen chloride; (b) admixing (i) magnesium hydroxide, magnesium oxide and/or MgCl(OH), (ii) CaCl₂ and (iii) carbon dioxide produced by the source in a second admixture under conditions suitable to form (iv) calcium carbonate, (v) a magnesium chloride salt, and (vi) water; (c) separating the calcium carbonate from the second admixture; and (d) admixing a Group 2 silicate mineral with hydrogen chloride under conditions suitable to form a Group 2 chloride salt, water, and silicon dioxide, where some the hydrogen chloride in this step is obtained from step (a) and wherein some of the hydrogen chloride is obtained from a chlor-alkali electrolytic cell, whereby the carbon dioxide is sequestered into a mineral product form.
 2. The method of claim 1, wherein some or all of the hydrogen chloride of step (a) is admixed with water to form hydrochloric acid.
 3. The method of claim 1, where some or all of the magnesium hydroxide, magnesium oxide and/or MgCl(OH) of step (b)(i) is obtained from step (a)(i).
 4. The method of claim 1, where some or all of the water in step (a) is present in the form of a hydrate of the magnesium chloride salt.
 5. The method of claim 1, wherein step (a) occurs in one, two or three chambers.
 6. The method of claim 1, wherein step (a) occurs in one chamber.
 7. The method of claim 1, wherein the magnesium hydroxide, magnesium oxide and/or MgCl(OH) of step (a)(i) is greater than 90% by weight Mg(OH)Cl.
 8. The method of claim 1, wherein the magnesium chloride salt is greater than 90% by weight MgCl₂.6(H₂O).
 9. The method of claim 1, wherein step (d) further comprises agitating the Group 2 silicate mineral with the hydrochloric acid.
 10. The method of claim 1, where some or all of the magnesium chloride salt in step (a) is obtained from step (d).
 11. The method of claim 1, further comprising a separation step, wherein the silicon dioxide is removed from the Group 2 chloride salt formed in step (d).
 12. The method of claim 1, where some or all of the water of step (a) is obtained from the water of step (d).
 13. The method of claim 1, wherein the Group 2 silicate mineral of step (d) comprises a Group 2 inosilicate.
 14. The method of claim 1, wherein the Group 2 silicate mineral of step (d) comprises CaSiO₃.
 15. The method of claim 1, wherein the Group 2 silicate mineral of step (d) comprises MgSiO₃.
 16. The method of claim 1, wherein the Group 2 silicate mineral of step (d) comprises olivine.
 17. The method of claim 1, wherein the Group 2 silicate mineral of step (d) comprises serpentine.
 18. The method of claim 1, wherein the Group 2 silicate mineral of step (d) comprises sepiolite, enstatite, diopside, and/or tremolite.
 19. The method of claim 1, wherein the Group 2 silicate further comprises mineralized iron and or manganese.
 20. The method according to claim 1, wherein step (b) further comprises admixing CaCl₂ and water to the second admixture.
 21. The method according to claim 1, further comprising: (e) heating a magnesium chloride salt and water in a third admixture to form (i) magnesium hydroxide, magnesium oxide and/or MgCl(OH) and (ii) hydrogen chloride; (f) admixing (i) magnesium hydroxide, magnesium oxide and/or MgCl(OH), (ii) CaCl₂ and (iii) carbon dioxide produced by the source in a fourth admixture under conditions suitable to form (iv) calcium carbonate, (v) a magnesium chloride salt, and (vi) water; (g) separating the calcium carbonate from the fourth admixture; and (h) admixing a Group 2 silicate mineral with hydrogen chloride under conditions suitable to form a Group 2 chloride salt, water, and silicon dioxide, where some or all of the hydrogen chloride in this step is obtained from step (e), whereby the carbon dioxide is sequestered into a mineral product form.
 22. The method of claim 21, wherein all of the hydrogen chloride in step (h) is obtained from step (e).
 23. The method according to claim 1, further comprising: admixing (i) sodium hydroxide produced from the chlor-alkali electrolytic cell, and (ii) the carbon dioxide produced by the source in a fifth admixture under conditions suitable to form (iii) sodium bicarbonate and/or sodium carbonate. 